From b759483e31fc137712bf7a66b062d01284b3c00b Mon Sep 17 00:00:00 2001
From: Peter van der Zee <github-public@qfox.nl>
Date: Mon, 19 Oct 2020 12:20:21 +0200
Subject: [PATCH 1/2] perf: implement shouldOnCreateNode for all our plugins

---
 benchmarks/gabe-csv-markdown/gatsby-node.js   |  31 +++---
 benchmarks/markdown_id/gatsby-node.js         |  23 ++--
 benchmarks/markdown_slug/gatsby-node.js       |  23 ++--
 benchmarks/md/gatsby-node.js                  |  32 +++---
 benchmarks/mdx/gatsby-node.js                 |  18 ++--
 benchmarks/source-agilitycms/gatsby-node.js   | 100 ++++++++++--------
 benchmarks/source-cosmicjs/gatsby-node.js     |  14 ++-
 benchmarks/source-datocms/gatsby-node.js      |   8 +-
 benchmarks/source-drupal/gatsby-node.js       |   8 +-
 benchmarks/source-flotiq/gatsby-node.js       |   8 +-
 packages/gatsby-plugin-mdx/gatsby-node.js     |  12 ++-
 .../gatsby/on-create-node.js                  |  35 +++---
 .../src/gatsby-node.js                        |  21 ++--
 .../gatsby-transformer-csv/src/gatsby-node.js |  20 ++--
 .../src/gatsby-node.js                        |  26 +++--
 .../src/gatsby-node.js                        |  40 ++++++-
 .../src/gatsby-node.js                        |  25 +++--
 .../src/gatsby-node.js                        |  16 ++-
 .../src/gatsby-node.js                        |  13 ++-
 .../src/gatsby-node.js                        |  15 ++-
 .../gatsby-transformer-pdf/src/gatsby-node.js |  13 ++-
 .../src/__tests__/on-node-create.js           |   2 +-
 .../src/gatsby-node.js                        |   7 +-
 .../src/on-node-create.js                     |  10 +-
 .../src/on-node-create.js                     |   4 +-
 .../src/gatsby-node.js                        |  20 ++--
 .../src/on-node-create.js                     |   8 +-
 .../src/gatsby-node.js                        |  17 ++-
 .../gatsby-transformer-xml/src/gatsby-node.js |  14 ++-
 .../src/gatsby-node.js                        |  13 ++-
 30 files changed, 386 insertions(+), 210 deletions(-)

diff --git a/benchmarks/gabe-csv-markdown/gatsby-node.js b/benchmarks/gabe-csv-markdown/gatsby-node.js
index e175aa95b70f4..689f0607142fd 100644
--- a/benchmarks/gabe-csv-markdown/gatsby-node.js
+++ b/benchmarks/gabe-csv-markdown/gatsby-node.js
@@ -42,21 +42,26 @@ exports.createPages = async ({ graphql, actions }) => {
   })
 }
 
+function unstable_shouldOnCreateNode({ node }) {
+  return node.internal.type === `GendataCsv`
+}
+
 // Not sure if there is a better way than to create a proxy node for markdown to pick up
 // I certainly can't get remark to to pick up csv nodes :(
-exports.onCreateNode = ({ node, actions }) => {
+function onCreateNode({ node, actions }) {
   const { createNode } = actions
 
-  if (node.internal.type === `GendataCsv`) {
-    createNode({
-      id: `${node.id}-MarkdownProxy`,
-      parent: node.id,
-      internal: {
-        type: `MarkdownProxy`,
-        mediaType: "text/markdown",
-        content: node.articleContent,
-        contentDigest: node.articleContent,
-      },
-    })
-  }
+  createNode({
+    id: `${node.id}-MarkdownProxy`,
+    parent: node.id,
+    internal: {
+      type: `MarkdownProxy`,
+      mediaType: "text/markdown",
+      content: node.articleContent,
+      contentDigest: node.articleContent,
+    },
+  })
 }
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+exports.onCreateNode = onCreateNode
diff --git a/benchmarks/markdown_id/gatsby-node.js b/benchmarks/markdown_id/gatsby-node.js
index 40a81a43188ce..268c09adf7a38 100644
--- a/benchmarks/markdown_id/gatsby-node.js
+++ b/benchmarks/markdown_id/gatsby-node.js
@@ -48,15 +48,20 @@ exports.createPages = async ({ graphql, actions }) => {
   })
 }
 
-exports.onCreateNode = ({ node, actions, getNode }) => {
+function unstable_shouldOnCreateNode({ node }) {
+  return node.internal.type === `MarkdownRemark`
+}
+
+function onCreateNode({ node, actions, getNode }) {
   const { createNodeField } = actions
 
-  if (node.internal.type === `MarkdownRemark`) {
-    const value = createFilePath({ node, getNode })
-    createNodeField({
-      name: `slug`,
-      node,
-      value,
-    })
-  }
+  const value = createFilePath({ node, getNode })
+  createNodeField({
+    name: `slug`,
+    node,
+    value,
+  })
 }
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+exports.onCreateNode = onCreateNode
diff --git a/benchmarks/markdown_slug/gatsby-node.js b/benchmarks/markdown_slug/gatsby-node.js
index 8c980141d3a5b..216953ccd0661 100644
--- a/benchmarks/markdown_slug/gatsby-node.js
+++ b/benchmarks/markdown_slug/gatsby-node.js
@@ -47,15 +47,20 @@ exports.createPages = async ({ graphql, actions }) => {
   })
 }
 
-exports.onCreateNode = ({ node, actions, getNode }) => {
+function unstable_shouldOnCreateNode({ node }) {
+  return node.internal.type === `MarkdownRemark`
+}
+
+function onCreateNode({ node, actions, getNode }) {
   const { createNodeField } = actions
 
-  if (node.internal.type === `MarkdownRemark`) {
-    const value = createFilePath({ node, getNode })
-    createNodeField({
-      name: `slug`,
-      node,
-      value,
-    })
-  }
+  const value = createFilePath({ node, getNode })
+  createNodeField({
+    name: `slug`,
+    node,
+    value,
+  })
 }
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+exports.onCreateNode = onCreateNode
diff --git a/benchmarks/md/gatsby-node.js b/benchmarks/md/gatsby-node.js
index 4855458bd3b53..15efb43402ec2 100644
--- a/benchmarks/md/gatsby-node.js
+++ b/benchmarks/md/gatsby-node.js
@@ -1,20 +1,6 @@
 const path = require("path")
 const { createFilePath } = require("gatsby-source-filesystem")
 
-exports.onCreateNode = ({ node, actions, getNode }) => {
-  const { createNodeField } = actions
-
-  if (node.internal.type === "MarkdownRemark") {
-    const value = createFilePath({ node, getNode })
-
-    createNodeField({
-      name: "path",
-      node,
-      value,
-    })
-  }
-}
-
 exports.createPages = async ({ graphql, actions, reporter }) => {
   const { createPage } = actions
 
@@ -47,3 +33,21 @@ exports.createPages = async ({ graphql, actions, reporter }) => {
     })
   })
 }
+
+function unstable_shouldOnCreateNode({ node }) {
+  return node.internal.type === `MarkdownRemark`
+}
+
+function onCreateNode({ node, actions, getNode }) {
+  const { createNodeField } = actions
+
+  const value = createFilePath({ node, getNode })
+  createNodeField({
+    name: `path`,
+    node,
+    value,
+  })
+}
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+exports.onCreateNode = onCreateNode
diff --git a/benchmarks/mdx/gatsby-node.js b/benchmarks/mdx/gatsby-node.js
index 1388e4c84e7e6..5b013e69efb03 100644
--- a/benchmarks/mdx/gatsby-node.js
+++ b/benchmarks/mdx/gatsby-node.js
@@ -1,18 +1,20 @@
 const path = require("path")
 const { createFilePath } = require("gatsby-source-filesystem")
 
+exports.unstable_shouldOnCreateNode = function ({ node }) {
+  return node.internal.type === "Mdx"
+}
+
 exports.onCreateNode = ({ node, actions, getNode }) => {
   const { createNodeField } = actions
 
-  if (node.internal.type === "Mdx") {
-    const value = createFilePath({ node, getNode })
+  const value = createFilePath({ node, getNode })
 
-    createNodeField({
-      name: "path",
-      node,
-      value,
-    })
-  }
+  createNodeField({
+    name: "path",
+    node,
+    value,
+  })
 }
 
 exports.createPages = async ({ graphql, actions, reporter }) => {
diff --git a/benchmarks/source-agilitycms/gatsby-node.js b/benchmarks/source-agilitycms/gatsby-node.js
index 86648f9fb6261..70748d6705f90 100644
--- a/benchmarks/source-agilitycms/gatsby-node.js
+++ b/benchmarks/source-agilitycms/gatsby-node.js
@@ -1,57 +1,69 @@
-const agility = require('./src/agility/utils')
+const agility = require("./src/agility/utils")
 const { createRemoteFileNode } = require("gatsby-source-filesystem")
 
 //gatsy-node.js
 //CREATE RESOLVERS *******************************************************************************************
 exports.createResolvers = (args) => {
+  const {
+    createResolvers,
+    getNode,
+    createNodeId,
+    createNode,
+    createContentDigest,
+    configOptions,
+  } = args
 
-	const { createResolvers, getNode, createNodeId, createNode, createContentDigest, configOptions } = args;
+  const resolvers = {
+    //on the 'agilityPost' node type...
+    agilityPost: {
+      //get the sitemap node that represents this item - useful for retrieving the URL for the item
+      sitemapNode: agility.getDynamicPageItemSitemapNode(),
 
-	const resolvers = {
-		//on the 'agilityPost' node type...
-		agilityPost: {
-			//get the sitemap node that represents this item - useful for retrieving the URL for the item
-			sitemapNode: agility.getDynamicPageItemSitemapNode(),
+      //[Not Implemented]
+      //if we had a linked content field for 'author', this is how we'd get the author for this post in a single GraphQl query
+      //linkedContent_agilityAuthor: agility.getLinkedContentItem({ type: 'agilityAuthor', linkedContentFieldName: 'author' })
+    },
 
-			//[Not Implemented]
-			//if we had a linked content field for 'author', this is how we'd get the author for this post in a single GraphQl query
-			//linkedContent_agilityAuthor: agility.getLinkedContentItem({ type: 'agilityAuthor', linkedContentFieldName: 'author' })
-		},
+    //[Not Implemented]
+    //if we had an 'Image Slider' module and it had a list of slides via a linked content field called 'slides', this is how we'd retrieve a list of those slides in a single GraphQL query
+    // agilityImageSlider: {
+    //     linkedContent_agilitySlides: agility.getLinkedContentList({ type: 'agilitySlide', linkedContentFieldName: 'slides' })
+    // }
+  }
+  createResolvers(resolvers)
+}
 
-		//[Not Implemented]
-		//if we had an 'Image Slider' module and it had a list of slides via a linked content field called 'slides', this is how we'd retrieve a list of those slides in a single GraphQL query
-		// agilityImageSlider: {
-		//     linkedContent_agilitySlides: agility.getLinkedContentList({ type: 'agilitySlide', linkedContentFieldName: 'slides' })
-		// }
-	}
-	createResolvers(resolvers)
+function unstable_shouldOnCreateNode({node}) {
+  return (
+    node.properties && node.properties.referenceName.toLowerCase() === `posts`
+  )
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 exports.onCreateNode = async ({
-	node,
-	actions: { createNode },
-	store,
-	cache,
-	createNodeId,
+  node,
+  actions: { createNode },
+  store,
+  cache,
+  createNodeId,
 }) => {
-
-	if (node.properties
-		&& node.properties.referenceName.toLowerCase() === `posts`) {
-		let field = "image"
-		let imageUrl = node.customFields[field]
-		if (imageUrl) {
-			let fileNode = await createRemoteFileNode({
-				url: imageUrl, // string that points to the URL of the image
-				parentNodeId: node.id, // id of the parent node of the fileNode you are going to create
-				createNode, // helper function in gatsby-node to generate the node
-				createNodeId, // helper function in gatsby-node to generate the node id
-				cache, // Gatsby's cache
-				store, // Gatsby's redux store
-			})
-			// if the file was created, attach the new node to the parent node
-			if (fileNode) {
-				node.customFields[`${field}LocalImg___NODE`] = fileNode.id
-			}
-		}
-	}
-}
\ No newline at end of file
+  if (unstable_shouldOnCreateNode({node})) {
+    let field = "image"
+    let imageUrl = node.customFields[field]
+    if (imageUrl) {
+      let fileNode = await createRemoteFileNode({
+        url: imageUrl, // string that points to the URL of the image
+        parentNodeId: node.id, // id of the parent node of the fileNode you are going to create
+        createNode, // helper function in gatsby-node to generate the node
+        createNodeId, // helper function in gatsby-node to generate the node id
+        cache, // Gatsby's cache
+        store, // Gatsby's redux store
+      })
+      // if the file was created, attach the new node to the parent node
+      if (fileNode) {
+        node.customFields[`${field}LocalImg___NODE`] = fileNode.id
+      }
+    }
+  }
+}
diff --git a/benchmarks/source-cosmicjs/gatsby-node.js b/benchmarks/source-cosmicjs/gatsby-node.js
index 40ab25a22e39b..4912615a66686 100644
--- a/benchmarks/source-cosmicjs/gatsby-node.js
+++ b/benchmarks/source-cosmicjs/gatsby-node.js
@@ -1,9 +1,15 @@
 const kebabCase = require(`lodash.kebabcase`)
 
+function unstable_shouldOnCreateNode({node}) {
+  return node.internal.type === "node__article"
+}
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 exports.onCreateNode = ({ actions, node }) => {
   const { createNodeField } = actions
 
-  if (node.internal.type === 'node__article') {
+  if (unstable_shouldOnCreateNode({node})) {
     createNodeField({ node, name: "slug", value: kebabCase(node.title) })
   }
 }
@@ -27,13 +33,13 @@ exports.createPages = async ({ actions, graphql, reporter }) => {
     reporter.panicOnBuild(result.errors)
   }
 
-  result.data.articles.edges.map(article => {
+  result.data.articles.edges.map((article) => {
     createPage({
       path: article.node.slug,
       component: require.resolve(`./src/templates/article.js`),
       context: {
         slug: article.node.slug,
-      }
+      },
     })
   })
-}
\ No newline at end of file
+}
diff --git a/benchmarks/source-datocms/gatsby-node.js b/benchmarks/source-datocms/gatsby-node.js
index 75f590e92c7a0..4e53a79c06bb2 100644
--- a/benchmarks/source-datocms/gatsby-node.js
+++ b/benchmarks/source-datocms/gatsby-node.js
@@ -1,9 +1,15 @@
 const kebabCase = require(`lodash.kebabcase`)
 
+function unstable_shouldOnCreateNode({node}) {
+  return node.internal.type === `node__article`
+}
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 exports.onCreateNode = ({ actions, node }) => {
   const { createNodeField } = actions
 
-  if (node.internal.type === `node__article`) {
+  if (unstable_shouldOnCreateNode({node})) {
     createNodeField({ node, name: `slug`, value: kebabCase(node.title) })
   }
 }
diff --git a/benchmarks/source-drupal/gatsby-node.js b/benchmarks/source-drupal/gatsby-node.js
index d161fa76d59a7..ca3007f4bad09 100644
--- a/benchmarks/source-drupal/gatsby-node.js
+++ b/benchmarks/source-drupal/gatsby-node.js
@@ -1,9 +1,15 @@
 const kebabCase = require(`lodash.kebabcase`)
 
+function unstable_shouldOnCreateNode({node}) {
+  return node.internal.type === `node__article`
+}
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 exports.onCreateNode = ({ actions, node }) => {
   const { createNodeField } = actions
 
-  if (node.internal.type === "node__article") {
+  if (unstable_shouldOnCreateNode({node})) {
     createNodeField({ node, name: "slug", value: kebabCase(node.title) })
   }
 }
diff --git a/benchmarks/source-flotiq/gatsby-node.js b/benchmarks/source-flotiq/gatsby-node.js
index 26f4f739e91fe..7b29474d0da07 100644
--- a/benchmarks/source-flotiq/gatsby-node.js
+++ b/benchmarks/source-flotiq/gatsby-node.js
@@ -1,9 +1,15 @@
 const kebabCase = require(`lodash.kebabcase`)
 
+function unstable_shouldOnCreateNode({node}) {
+  return node.internal.type === `node__article`
+}
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 exports.onCreateNode = ({ actions, node }) => {
   const { createNodeField } = actions
 
-  if (node.internal.type === "node__article") {
+  if (unstable_shouldOnCreateNode({node})) {
     createNodeField({ node, name: "slug", value: kebabCase(node.title) })
   }
 }
diff --git a/packages/gatsby-plugin-mdx/gatsby-node.js b/packages/gatsby-plugin-mdx/gatsby-node.js
index 0035204c58d04..247fbaf343302 100644
--- a/packages/gatsby-plugin-mdx/gatsby-node.js
+++ b/packages/gatsby-plugin-mdx/gatsby-node.js
@@ -4,15 +4,25 @@ const { MDX_SCOPES_LOCATION } = require(`./constants`)
 const defaultOptions = require(`./utils/default-options`)
 const fs = require(`fs`)
 
+const {
+  onCreateNode,
+  unstable_shouldOnCreateNode
+} = require(`./gatsby/on-create-node`)
+
 /**
  * Create Mdx types and resolvers
  */
 exports.sourceNodes = require(`./gatsby/source-nodes`)
 
+/**
+ * Check whether the Create Mdx nodes from MDX files.
+ */
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 /**
  * Create Mdx nodes from MDX files.
  */
-exports.onCreateNode = require(`./gatsby/on-create-node`)
+exports.onCreateNode = onCreateNode
 
 /**
  * Add frontmatter as page context for MDX pages
diff --git a/packages/gatsby-plugin-mdx/gatsby/on-create-node.js b/packages/gatsby-plugin-mdx/gatsby/on-create-node.js
index b33d246c6f6d9..36258385bd62c 100644
--- a/packages/gatsby-plugin-mdx/gatsby/on-create-node.js
+++ b/packages/gatsby-plugin-mdx/gatsby/on-create-node.js
@@ -10,7 +10,26 @@ const { findImports } = require(`../utils/gen-mdx`)
 
 const contentDigest = val => createContentDigest(val)
 
-module.exports = async (
+function unstable_shouldOnCreateNode({ node }, pluginOptions) {
+  const options = defaultOptions(pluginOptions)
+
+  return _unstable_shouldOnCreateNode({ node }, options)
+}
+
+function _unstable_shouldOnCreateNode({ node }, options) {
+  // options check to stop transformation of the node
+  if (options.shouldBlockNodeFromTransformation(node)) {
+    return false
+  }
+
+  return node.internal.type === `File`
+    ? options.extensions.includes(node.ext)
+    : options.mediaTypes.includes(node.internal.mediaType)
+}
+
+module.exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
+module.exports.onCreateNode = async (
   {
     node,
     loadNodeContent,
@@ -28,19 +47,7 @@ module.exports = async (
   const { createNode, createParentChildLink } = actions
   const options = defaultOptions(pluginOptions)
 
-  // options check to stop transformation of the node
-  if (options.shouldBlockNodeFromTransformation(node)) {
-    return
-  }
-
-  // if we shouldn't process this node, then return
-  if (
-    !(node.internal.type === `File` && options.extensions.includes(node.ext)) &&
-    !(
-      node.internal.type !== `File` &&
-      options.mediaTypes.includes(node.internal.mediaType)
-    )
-  ) {
+  if (!_unstable_shouldOnCreateNode({ node }, options)) {
     return
   }
 
diff --git a/packages/gatsby-transformer-asciidoc/src/gatsby-node.js b/packages/gatsby-transformer-asciidoc/src/gatsby-node.js
index 05a021f4e8a49..c1a0d8f828144 100644
--- a/packages/gatsby-transformer-asciidoc/src/gatsby-node.js
+++ b/packages/gatsby-transformer-asciidoc/src/gatsby-node.js
@@ -1,6 +1,16 @@
 const asciidoc = require(`asciidoctor`)()
 const _ = require(`lodash`)
 
+function unstable_shouldOnCreateNode({ node }, pluginOptions = {}) {
+  const extensionsConfig = pluginOptions.fileExtensions
+
+  // make extensions configurable and use adoc and asciidoc as default
+  const supportedExtensions =
+    extensionsConfig instanceof Array ? extensionsConfig : [`adoc`, `asciidoc`]
+
+  return supportedExtensions.includes(node.extension)
+}
+
 async function onCreateNode(
   {
     node,
@@ -13,15 +23,7 @@ async function onCreateNode(
   },
   pluginOptions
 ) {
-  const extensionsConfig = pluginOptions.fileExtensions
-
-  // make extensions configurable and use adoc and asciidoc as default
-  const supportedExtensions =
-    typeof extensionsConfig !== `undefined` && extensionsConfig instanceof Array
-      ? extensionsConfig
-      : [`adoc`, `asciidoc`]
-
-  if (!supportedExtensions.includes(node.extension)) {
+  if (!unstable_shouldOnCreateNode({ node }, pluginOptions)) {
     return
   }
 
@@ -138,4 +140,5 @@ const extractPageAttributes = allAttributes =>
     return pageAttributes
   }, {})
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-csv/src/gatsby-node.js b/packages/gatsby-transformer-csv/src/gatsby-node.js
index cefed79dc5819..ca06e2dd78211 100644
--- a/packages/gatsby-transformer-csv/src/gatsby-node.js
+++ b/packages/gatsby-transformer-csv/src/gatsby-node.js
@@ -8,20 +8,25 @@ const convertToJson = (data, options) =>
     .fromString(data)
     .then(jsonData => jsonData, new Error(`CSV to JSON conversion failed!`))
 
+function unstable_shouldOnCreateNode({ node }, pluginOptions = {}) {
+  const { extension } = node
+  const { extensions } = pluginOptions
+
+  return extensions ? extensions.includes(extension) : extension === `csv`
+}
+
 async function onCreateNode(
   { node, actions, loadNodeContent, createNodeId, createContentDigest },
   pluginOptions
 ) {
+  if (!unstable_shouldOnCreateNode({ node }, pluginOptions)) {
+    return
+  }
+
   const { createNode, createParentChildLink } = actions
 
   // Destructure out our custom options
-  const { typeName, nodePerFile, extensions, ...options } = pluginOptions || {}
-
-  // Filter out unwanted content
-  const filterExtensions = extensions ?? [`csv`]
-  if (!filterExtensions.includes(node.extension)) {
-    return
-  }
+  const { typeName, nodePerFile, ...options } = pluginOptions || {}
 
   // Load file contents
   const content = await loadNodeContent(node)
@@ -79,4 +84,5 @@ async function onCreateNode(
   return
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-documentationjs/src/gatsby-node.js b/packages/gatsby-transformer-documentationjs/src/gatsby-node.js
index ee4976f443fb9..1bf9f45afad61 100644
--- a/packages/gatsby-transformer-documentationjs/src/gatsby-node.js
+++ b/packages/gatsby-transformer-documentationjs/src/gatsby-node.js
@@ -185,25 +185,29 @@ exports.createResolvers = ({ createResolvers }) => {
   })
 }
 
+function unstable_shouldOnCreateNode({ node }) {
+  return (
+    node.internal.type === `File` &&
+    (node.internal.mediaType === `application/javascript` ||
+      node.extension === `tsx` ||
+      node.extension === `ts`)
+  )
+}
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 /**
  * Implement the onCreateNode API to create documentation.js nodes
  * @param {Object} super this is a super param
  */
 exports.onCreateNode = async ({ node, actions, ...helpers }) => {
-  const { createNodeId, createContentDigest } = helpers
-  const { createNode, createParentChildLink } = actions
-
-  if (
-    node.internal.type !== `File` ||
-    !(
-      node.internal.mediaType === `application/javascript` ||
-      node.extension === `tsx` ||
-      node.extension === `ts`
-    )
-  ) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return null
   }
 
+  const { createNodeId, createContentDigest } = helpers
+  const { createNode, createParentChildLink } = actions
+
   let documentationJson
   try {
     documentationJson = await documentation.build(node.absolutePath, {
diff --git a/packages/gatsby-transformer-excel/src/gatsby-node.js b/packages/gatsby-transformer-excel/src/gatsby-node.js
index d85b7b2b91984..dfe6fbdaacd9f 100644
--- a/packages/gatsby-transformer-excel/src/gatsby-node.js
+++ b/packages/gatsby-transformer-excel/src/gatsby-node.js
@@ -9,17 +9,46 @@ function _loadNodeContent(fileNode, fallback) {
     : fallback(fileNode)
 }
 
+const extensions = [
+  `xls`,
+  `xlsx`,
+  `xlsm`,
+  `xlsb`,
+  `xml`,
+  `xlw`,
+  `xlc`,
+  `csv`,
+  `txt`,
+  `dif`,
+  `sylk`,
+  `slk`,
+  `prn`,
+  `ods`,
+  `fods`,
+  `uos`,
+  `dbf`,
+  `wks`,
+  `123`,
+  `wq1`,
+  `qpw`,
+  `htm`,
+  `html`,
+]
+
+function unstable_shouldOnCreateNode({ node }) {
+  return extensions.includes((node.extension || ``).toLowerCase())
+}
+
 async function onCreateNode(
   { node, actions, loadNodeContent, createNodeId, createContentDigest },
   options = {}
 ) {
-  const { createNode, createParentChildLink } = actions
-  const extensions = `xls|xlsx|xlsm|xlsb|xml|xlw|xlc|csv|txt|dif|sylk|slk|prn|ods|fods|uos|dbf|wks|123|wq1|qpw|htm|html`.split(
-    `|`
-  )
-  if (extensions.indexOf((node.extension || ``).toLowerCase()) == -1) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
+
+  const { createNode, createParentChildLink } = actions
+
   // Load binary string
   const content = await _loadNodeContent(node, loadNodeContent)
 
@@ -86,4 +115,5 @@ async function onCreateNode(
   return
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-hjson/src/gatsby-node.js b/packages/gatsby-transformer-hjson/src/gatsby-node.js
index ab009bc55b551..d47928241a9d9 100644
--- a/packages/gatsby-transformer-hjson/src/gatsby-node.js
+++ b/packages/gatsby-transformer-hjson/src/gatsby-node.js
@@ -2,6 +2,16 @@ const _ = require(`lodash`)
 const path = require(`path`)
 const HJSON = require(`hjson`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // We only care about HJSON content.
+  // NOTE the mime package does not recognize HJSON yet
+  // See RFC https://hjson.org/rfc.html#rfc.section.1.3
+  return (
+    node.internal.mediaType === `text/hjson` ||
+    node.internal.mediaType === `application/hjson`
+  )
+}
+
 async function onCreateNode({
   node,
   actions,
@@ -9,6 +19,10 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
+  if (!unstable_shouldOnCreateNode({ node })) {
+    return
+  }
+
   const { createNode, createParentChildLink } = actions
 
   function transformObject(obj, id, type) {
@@ -27,16 +41,6 @@ async function onCreateNode({
     createParentChildLink({ parent: node, child: jsonNode })
   }
 
-  // We only care about HJSON content.
-  // NOTE the mime package does not recognize HJSON yet
-  // See RFC https://hjson.org/rfc.html#rfc.section.1.3
-  if (
-    node.internal.mediaType !== `text/hjson` &&
-    node.internal.mediaType !== `application/hjson`
-  ) {
-    return
-  }
-
   const content = await loadNodeContent(node)
   const parsedContent = HJSON.parse(content)
 
@@ -59,4 +63,5 @@ async function onCreateNode({
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-javascript-frontmatter/src/gatsby-node.js b/packages/gatsby-transformer-javascript-frontmatter/src/gatsby-node.js
index 420caba781c0b..e15a64a2f1f46 100644
--- a/packages/gatsby-transformer-javascript-frontmatter/src/gatsby-node.js
+++ b/packages/gatsby-transformer-javascript-frontmatter/src/gatsby-node.js
@@ -2,20 +2,25 @@ const _ = require(`lodash`)
 const babylon = require(`@babel/parser`)
 const traverse = require(`@babel/traverse`).default
 
+const fileExtsToProcess = [`js`, `jsx`, `ts`, `tsx`]
+
+function unstable_shouldOnCreateNode({ node }) {
+  // This only processes JavaScript and TypeScript files.
+  return fileExtsToProcess.includes(node.extension)
+}
+
 async function onCreateNode({
   node,
   actions,
   loadNodeContent,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-  const fileExtsToProcess = [`js`, `jsx`, `ts`, `tsx`]
-
-  // This only processes JavaScript and TypeScript files.
-  if (!_.includes(fileExtsToProcess, node.extension)) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   const code = await loadNodeContent(node)
   const options = {
     sourceType: `module`,
@@ -135,4 +140,5 @@ async function onCreateNode({
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-javascript-static-exports/src/gatsby-node.js b/packages/gatsby-transformer-javascript-static-exports/src/gatsby-node.js
index 3ff8d86825258..efdbdddaf2129 100644
--- a/packages/gatsby-transformer-javascript-static-exports/src/gatsby-node.js
+++ b/packages/gatsby-transformer-javascript-static-exports/src/gatsby-node.js
@@ -2,6 +2,11 @@ const _ = require(`lodash`)
 const babylon = require(`@babel/parser`)
 const traverse = require(`@babel/traverse`).default
 
+function unstable_shouldOnCreateNode({ node }) {
+  // This only processes JavaScript files.
+  return node.internal.mediaType === `application/javascript`
+}
+
 async function onCreateNode({
   node,
   getNode,
@@ -10,13 +15,12 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-
-  // This only processes JavaScript files.
-  if (node.internal.mediaType !== `application/javascript`) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   const code = await loadNodeContent(node)
   const options = {
     sourceType: `unambigious`,
@@ -150,4 +154,5 @@ async function onCreateNode({
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-json/src/gatsby-node.js b/packages/gatsby-transformer-json/src/gatsby-node.js
index 65ea7c33193ff..b69fc66a03170 100644
--- a/packages/gatsby-transformer-json/src/gatsby-node.js
+++ b/packages/gatsby-transformer-json/src/gatsby-node.js
@@ -1,10 +1,19 @@
 const _ = require(`lodash`)
 const path = require(`path`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // We only care about JSON content.
+  return node.internal.mediaType === `application/json`
+}
+
 async function onCreateNode(
   { node, actions, loadNodeContent, createNodeId, createContentDigest },
   pluginOptions
 ) {
+  if (!unstable_shouldOnCreateNode({ node })) {
+    return
+  }
+
   function getType({ node, object, isArray }) {
     if (pluginOptions && _.isFunction(pluginOptions.typeName)) {
       return pluginOptions.typeName({ node, object, isArray })
@@ -36,11 +45,6 @@ async function onCreateNode(
 
   const { createNode, createParentChildLink } = actions
 
-  // We only care about JSON content.
-  if (node.internal.mediaType !== `application/json`) {
-    return
-  }
-
   const content = await loadNodeContent(node)
   let parsedContent
   try {
@@ -71,4 +75,5 @@ async function onCreateNode(
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-pdf/src/gatsby-node.js b/packages/gatsby-transformer-pdf/src/gatsby-node.js
index 1c26439b939fe..17857a30a4fb1 100644
--- a/packages/gatsby-transformer-pdf/src/gatsby-node.js
+++ b/packages/gatsby-transformer-pdf/src/gatsby-node.js
@@ -1,6 +1,11 @@
 const Promise = require(`bluebird`)
 const PDFParser = require(`pdf2json`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // Filter out non-pdf content
+  return node.extension === `pdf`
+}
+
 const convertToJson = path =>
   new Promise((res, rej) => {
     const pdfParser = new PDFParser(this, 1)
@@ -21,13 +26,12 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-
-  // Filter out non-pdf content
-  if (node.extension !== `pdf`) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   let parsedContent = await convertToJson(node.absolutePath)
 
   const pdfNode = {
@@ -46,4 +50,5 @@ async function onCreateNode({
   createParentChildLink({ parent: node, child: pdfNode })
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-react-docgen/src/__tests__/on-node-create.js b/packages/gatsby-transformer-react-docgen/src/__tests__/on-node-create.js
index 28025d35a77ea..09b3db08aefe0 100644
--- a/packages/gatsby-transformer-react-docgen/src/__tests__/on-node-create.js
+++ b/packages/gatsby-transformer-react-docgen/src/__tests__/on-node-create.js
@@ -1,6 +1,6 @@
 import fs from "fs"
 import { groupBy } from "lodash"
-import onCreateNode from "../on-node-create"
+import { onCreateNode } from "../on-node-create"
 import path from "path"
 
 const readFile = file =>
diff --git a/packages/gatsby-transformer-react-docgen/src/gatsby-node.js b/packages/gatsby-transformer-react-docgen/src/gatsby-node.js
index 16650dcafbac8..c522a84d3679a 100644
--- a/packages/gatsby-transformer-react-docgen/src/gatsby-node.js
+++ b/packages/gatsby-transformer-react-docgen/src/gatsby-node.js
@@ -1,2 +1,7 @@
-exports.onCreateNode = require(`./on-node-create`).default
+const {
+  onCreateNode,
+  unstable_shouldOnCreateNode,
+} = require(`./on-node-create`)
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+exports.onCreateNode = onCreateNode
 exports.setFieldsOnGraphQLNodeType = require(`./extend-node-type`).default
diff --git a/packages/gatsby-transformer-react-docgen/src/on-node-create.js b/packages/gatsby-transformer-react-docgen/src/on-node-create.js
index 197197860956d..8ecd14e102a32 100644
--- a/packages/gatsby-transformer-react-docgen/src/on-node-create.js
+++ b/packages/gatsby-transformer-react-docgen/src/on-node-create.js
@@ -88,7 +88,11 @@ function createPropNodes(
   return node
 }
 
-export default async function onCreateNode(
+export function unstable_shouldOnCreateNode({ node }) {
+  return canParse(node)
+}
+
+export async function onCreateNode(
   {
     node,
     loadNodeContent,
@@ -99,10 +103,10 @@ export default async function onCreateNode(
   },
   pluginOptions
 ) {
-  const { createNode, createParentChildLink } = actions
-
   if (!canParse(node)) return
 
+  const { createNode, createParentChildLink } = actions
+
   const content = await loadNodeContent(node)
 
   let components
diff --git a/packages/gatsby-transformer-remark/src/on-node-create.js b/packages/gatsby-transformer-remark/src/on-node-create.js
index b47dce011f945..faa91945fb742 100644
--- a/packages/gatsby-transformer-remark/src/on-node-create.js
+++ b/packages/gatsby-transformer-remark/src/on-node-create.js
@@ -19,13 +19,13 @@ module.exports.onCreateNode = async function onCreateNode(
   },
   pluginOptions
 ) {
-  const { createNode, createParentChildLink } = actions
-
   // We only care about markdown content.
   if (!unstable_shouldOnCreateNode({ node })) {
     return {}
   }
 
+  const { createNode, createParentChildLink } = actions
+
   const content = await loadNodeContent(node)
 
   try {
diff --git a/packages/gatsby-transformer-screenshot/src/gatsby-node.js b/packages/gatsby-transformer-screenshot/src/gatsby-node.js
index 280082221e6a1..400ff9c7b66f9 100644
--- a/packages/gatsby-transformer-screenshot/src/gatsby-node.js
+++ b/packages/gatsby-transformer-screenshot/src/gatsby-node.js
@@ -76,21 +76,27 @@ exports.onPreBootstrap = (
   })
 }
 
-exports.onCreateNode = async (
-  { node, actions, store, cache, createNodeId, createContentDigest, getCache },
-  pluginOptions
-) => {
-  const { createNode, createParentChildLink } = actions
-
+function unstable_shouldOnCreateNode({ node }, pluginOptions) {
   /*
    * Check if node is of a type we care about, and has a url field
    * (originally only checked sites.yml, hence including by default)
    */
   const validNodeTypes = [`SitesYaml`].concat(pluginOptions.nodeTypes || [])
-  if (!validNodeTypes.includes(node.internal.type) || !node.url) {
+  return validNodeTypes.includes(node.internal.type) && node.url
+}
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
+exports.onCreateNode = async (
+  { node, actions, store, cache, createNodeId, createContentDigest, getCache },
+  pluginOptions
+) => {
+  if (!unstable_shouldOnCreateNode({ node }, pluginOptions)) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   try {
     const screenshotNode = await new Promise((resolve, reject) => {
       screenshotQueue
diff --git a/packages/gatsby-transformer-sharp/src/on-node-create.js b/packages/gatsby-transformer-sharp/src/on-node-create.js
index 30d319187cbf3..035627dcffcf8 100644
--- a/packages/gatsby-transformer-sharp/src/on-node-create.js
+++ b/packages/gatsby-transformer-sharp/src/on-node-create.js
@@ -4,17 +4,19 @@ function unstable_shouldOnCreateNode({ node }) {
   return !!supportedExtensions[node.extension]
 }
 
+module.exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 module.exports.onCreateNode = async function onCreateNode({
   node,
   actions,
   createNodeId,
 }) {
-  const { createNode, createParentChildLink } = actions
-
   if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   const imageNode = {
     id: createNodeId(`${node.id} >> ImageSharp`),
     children: [],
@@ -30,5 +32,3 @@ module.exports.onCreateNode = async function onCreateNode({
 
   return
 }
-
-module.exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
diff --git a/packages/gatsby-transformer-toml/src/gatsby-node.js b/packages/gatsby-transformer-toml/src/gatsby-node.js
index 944a538ffc2d0..df34d54c430ac 100644
--- a/packages/gatsby-transformer-toml/src/gatsby-node.js
+++ b/packages/gatsby-transformer-toml/src/gatsby-node.js
@@ -1,6 +1,13 @@
 const toml = require(`toml`)
 const _ = require(`lodash`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // Filter out non-toml content
+  // Currently TOML files are considered null in 'mime-db'
+  // Hence the extension test instead of mediaType test
+  return node.extension === `toml`
+}
+
 async function onCreateNode({
   node,
   actions,
@@ -8,13 +15,12 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-  // Filter out non-toml content
-  // Currently TOML files are considered null in 'mime-db'
-  // Hence the extension test instead of mediaType test
-  if (node.extension !== `toml`) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
+
+  const { createNode, createParentChildLink } = actions
+
   // Load TOML contents
   const content = await loadNodeContent(node)
   // Parse
@@ -45,4 +51,5 @@ async function onCreateNode({
   return
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-xml/src/gatsby-node.js b/packages/gatsby-transformer-xml/src/gatsby-node.js
index b603466b3e106..392a48563a20b 100644
--- a/packages/gatsby-transformer-xml/src/gatsby-node.js
+++ b/packages/gatsby-transformer-xml/src/gatsby-node.js
@@ -1,6 +1,11 @@
 const parseXml = require(`xml-parser`)
 const _ = require(`lodash`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // We only care about XML content.
+  return [`application/xml`, `text/xml`].includes(node.internal.mediaType)
+}
+
 async function onCreateNode({
   node,
   actions,
@@ -8,12 +13,12 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-
-  // We only care about XML content.
-  if (![`application/xml`, `text/xml`].includes(node.internal.mediaType)) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
+
+  const { createNode, createParentChildLink } = actions
+
   const rawXml = await loadNodeContent(node)
   const parsedXml = parseXml(rawXml)
   const nodeArray = parsedXml.root.children.map((obj, i) => {
@@ -42,4 +47,5 @@ async function onCreateNode({
   return
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-yaml/src/gatsby-node.js b/packages/gatsby-transformer-yaml/src/gatsby-node.js
index 9961d7303eaa1..850d65277c5b1 100644
--- a/packages/gatsby-transformer-yaml/src/gatsby-node.js
+++ b/packages/gatsby-transformer-yaml/src/gatsby-node.js
@@ -2,10 +2,18 @@ const jsYaml = require(`js-yaml`)
 const _ = require(`lodash`)
 const path = require(`path`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  return node.internal.mediaType === `text/yaml`
+}
+
 async function onCreateNode(
   { node, actions, loadNodeContent, createNodeId, createContentDigest },
   pluginOptions
 ) {
+  if (!unstable_shouldOnCreateNode({ node })) {
+    return
+  }
+
   function getType({ node, object, isArray }) {
     if (pluginOptions && _.isFunction(pluginOptions.typeName)) {
       return pluginOptions.typeName({ node, object, isArray })
@@ -37,10 +45,6 @@ async function onCreateNode(
 
   const { createNode, createParentChildLink } = actions
 
-  if (node.internal.mediaType !== `text/yaml`) {
-    return
-  }
-
   const content = await loadNodeContent(node)
   const parsedContent = jsYaml.load(content)
 
@@ -61,4 +65,5 @@ async function onCreateNode(
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode

From b7cbef95abf0a7cb98748571a784ee69e1a93b59 Mon Sep 17 00:00:00 2001
From: Peter van der Zee <github-public@qfox.nl>
Date: Tue, 20 Oct 2020 14:21:32 +0200
Subject: [PATCH 2/2] Drop changes in /benchmarks, fix typo

---
 benchmarks/gabe-csv-markdown/gatsby-node.js |  31 +++---
 benchmarks/markdown_id/gatsby-node.js       |  23 ++---
 benchmarks/markdown_slug/gatsby-node.js     |  23 ++---
 benchmarks/md/gatsby-node.js                |  32 +++----
 benchmarks/mdx/gatsby-node.js               |  18 ++--
 benchmarks/source-agilitycms/gatsby-node.js | 100 +++++++++-----------
 benchmarks/source-cosmicjs/gatsby-node.js   |  14 +--
 benchmarks/source-datocms/gatsby-node.js    |   8 +-
 benchmarks/source-drupal/gatsby-node.js     |   8 +-
 benchmarks/source-flotiq/gatsby-node.js     |   8 +-
 packages/gatsby-plugin-mdx/gatsby-node.js   |   2 +-
 11 files changed, 105 insertions(+), 162 deletions(-)

diff --git a/benchmarks/gabe-csv-markdown/gatsby-node.js b/benchmarks/gabe-csv-markdown/gatsby-node.js
index 689f0607142fd..e175aa95b70f4 100644
--- a/benchmarks/gabe-csv-markdown/gatsby-node.js
+++ b/benchmarks/gabe-csv-markdown/gatsby-node.js
@@ -42,26 +42,21 @@ exports.createPages = async ({ graphql, actions }) => {
   })
 }
 
-function unstable_shouldOnCreateNode({ node }) {
-  return node.internal.type === `GendataCsv`
-}
-
 // Not sure if there is a better way than to create a proxy node for markdown to pick up
 // I certainly can't get remark to to pick up csv nodes :(
-function onCreateNode({ node, actions }) {
+exports.onCreateNode = ({ node, actions }) => {
   const { createNode } = actions
 
-  createNode({
-    id: `${node.id}-MarkdownProxy`,
-    parent: node.id,
-    internal: {
-      type: `MarkdownProxy`,
-      mediaType: "text/markdown",
-      content: node.articleContent,
-      contentDigest: node.articleContent,
-    },
-  })
+  if (node.internal.type === `GendataCsv`) {
+    createNode({
+      id: `${node.id}-MarkdownProxy`,
+      parent: node.id,
+      internal: {
+        type: `MarkdownProxy`,
+        mediaType: "text/markdown",
+        content: node.articleContent,
+        contentDigest: node.articleContent,
+      },
+    })
+  }
 }
-
-exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
-exports.onCreateNode = onCreateNode
diff --git a/benchmarks/markdown_id/gatsby-node.js b/benchmarks/markdown_id/gatsby-node.js
index 268c09adf7a38..40a81a43188ce 100644
--- a/benchmarks/markdown_id/gatsby-node.js
+++ b/benchmarks/markdown_id/gatsby-node.js
@@ -48,20 +48,15 @@ exports.createPages = async ({ graphql, actions }) => {
   })
 }
 
-function unstable_shouldOnCreateNode({ node }) {
-  return node.internal.type === `MarkdownRemark`
-}
-
-function onCreateNode({ node, actions, getNode }) {
+exports.onCreateNode = ({ node, actions, getNode }) => {
   const { createNodeField } = actions
 
-  const value = createFilePath({ node, getNode })
-  createNodeField({
-    name: `slug`,
-    node,
-    value,
-  })
+  if (node.internal.type === `MarkdownRemark`) {
+    const value = createFilePath({ node, getNode })
+    createNodeField({
+      name: `slug`,
+      node,
+      value,
+    })
+  }
 }
-
-exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
-exports.onCreateNode = onCreateNode
diff --git a/benchmarks/markdown_slug/gatsby-node.js b/benchmarks/markdown_slug/gatsby-node.js
index 216953ccd0661..8c980141d3a5b 100644
--- a/benchmarks/markdown_slug/gatsby-node.js
+++ b/benchmarks/markdown_slug/gatsby-node.js
@@ -47,20 +47,15 @@ exports.createPages = async ({ graphql, actions }) => {
   })
 }
 
-function unstable_shouldOnCreateNode({ node }) {
-  return node.internal.type === `MarkdownRemark`
-}
-
-function onCreateNode({ node, actions, getNode }) {
+exports.onCreateNode = ({ node, actions, getNode }) => {
   const { createNodeField } = actions
 
-  const value = createFilePath({ node, getNode })
-  createNodeField({
-    name: `slug`,
-    node,
-    value,
-  })
+  if (node.internal.type === `MarkdownRemark`) {
+    const value = createFilePath({ node, getNode })
+    createNodeField({
+      name: `slug`,
+      node,
+      value,
+    })
+  }
 }
-
-exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
-exports.onCreateNode = onCreateNode
diff --git a/benchmarks/md/gatsby-node.js b/benchmarks/md/gatsby-node.js
index 15efb43402ec2..4855458bd3b53 100644
--- a/benchmarks/md/gatsby-node.js
+++ b/benchmarks/md/gatsby-node.js
@@ -1,6 +1,20 @@
 const path = require("path")
 const { createFilePath } = require("gatsby-source-filesystem")
 
+exports.onCreateNode = ({ node, actions, getNode }) => {
+  const { createNodeField } = actions
+
+  if (node.internal.type === "MarkdownRemark") {
+    const value = createFilePath({ node, getNode })
+
+    createNodeField({
+      name: "path",
+      node,
+      value,
+    })
+  }
+}
+
 exports.createPages = async ({ graphql, actions, reporter }) => {
   const { createPage } = actions
 
@@ -33,21 +47,3 @@ exports.createPages = async ({ graphql, actions, reporter }) => {
     })
   })
 }
-
-function unstable_shouldOnCreateNode({ node }) {
-  return node.internal.type === `MarkdownRemark`
-}
-
-function onCreateNode({ node, actions, getNode }) {
-  const { createNodeField } = actions
-
-  const value = createFilePath({ node, getNode })
-  createNodeField({
-    name: `path`,
-    node,
-    value,
-  })
-}
-
-exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
-exports.onCreateNode = onCreateNode
diff --git a/benchmarks/mdx/gatsby-node.js b/benchmarks/mdx/gatsby-node.js
index 5b013e69efb03..1388e4c84e7e6 100644
--- a/benchmarks/mdx/gatsby-node.js
+++ b/benchmarks/mdx/gatsby-node.js
@@ -1,20 +1,18 @@
 const path = require("path")
 const { createFilePath } = require("gatsby-source-filesystem")
 
-exports.unstable_shouldOnCreateNode = function ({ node }) {
-  return node.internal.type === "Mdx"
-}
-
 exports.onCreateNode = ({ node, actions, getNode }) => {
   const { createNodeField } = actions
 
-  const value = createFilePath({ node, getNode })
+  if (node.internal.type === "Mdx") {
+    const value = createFilePath({ node, getNode })
 
-  createNodeField({
-    name: "path",
-    node,
-    value,
-  })
+    createNodeField({
+      name: "path",
+      node,
+      value,
+    })
+  }
 }
 
 exports.createPages = async ({ graphql, actions, reporter }) => {
diff --git a/benchmarks/source-agilitycms/gatsby-node.js b/benchmarks/source-agilitycms/gatsby-node.js
index 70748d6705f90..86648f9fb6261 100644
--- a/benchmarks/source-agilitycms/gatsby-node.js
+++ b/benchmarks/source-agilitycms/gatsby-node.js
@@ -1,69 +1,57 @@
-const agility = require("./src/agility/utils")
+const agility = require('./src/agility/utils')
 const { createRemoteFileNode } = require("gatsby-source-filesystem")
 
 //gatsy-node.js
 //CREATE RESOLVERS *******************************************************************************************
 exports.createResolvers = (args) => {
-  const {
-    createResolvers,
-    getNode,
-    createNodeId,
-    createNode,
-    createContentDigest,
-    configOptions,
-  } = args
 
-  const resolvers = {
-    //on the 'agilityPost' node type...
-    agilityPost: {
-      //get the sitemap node that represents this item - useful for retrieving the URL for the item
-      sitemapNode: agility.getDynamicPageItemSitemapNode(),
+	const { createResolvers, getNode, createNodeId, createNode, createContentDigest, configOptions } = args;
 
-      //[Not Implemented]
-      //if we had a linked content field for 'author', this is how we'd get the author for this post in a single GraphQl query
-      //linkedContent_agilityAuthor: agility.getLinkedContentItem({ type: 'agilityAuthor', linkedContentFieldName: 'author' })
-    },
+	const resolvers = {
+		//on the 'agilityPost' node type...
+		agilityPost: {
+			//get the sitemap node that represents this item - useful for retrieving the URL for the item
+			sitemapNode: agility.getDynamicPageItemSitemapNode(),
 
-    //[Not Implemented]
-    //if we had an 'Image Slider' module and it had a list of slides via a linked content field called 'slides', this is how we'd retrieve a list of those slides in a single GraphQL query
-    // agilityImageSlider: {
-    //     linkedContent_agilitySlides: agility.getLinkedContentList({ type: 'agilitySlide', linkedContentFieldName: 'slides' })
-    // }
-  }
-  createResolvers(resolvers)
-}
+			//[Not Implemented]
+			//if we had a linked content field for 'author', this is how we'd get the author for this post in a single GraphQl query
+			//linkedContent_agilityAuthor: agility.getLinkedContentItem({ type: 'agilityAuthor', linkedContentFieldName: 'author' })
+		},
 
-function unstable_shouldOnCreateNode({node}) {
-  return (
-    node.properties && node.properties.referenceName.toLowerCase() === `posts`
-  )
+		//[Not Implemented]
+		//if we had an 'Image Slider' module and it had a list of slides via a linked content field called 'slides', this is how we'd retrieve a list of those slides in a single GraphQL query
+		// agilityImageSlider: {
+		//     linkedContent_agilitySlides: agility.getLinkedContentList({ type: 'agilitySlide', linkedContentFieldName: 'slides' })
+		// }
+	}
+	createResolvers(resolvers)
 }
 
-exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
-
 exports.onCreateNode = async ({
-  node,
-  actions: { createNode },
-  store,
-  cache,
-  createNodeId,
+	node,
+	actions: { createNode },
+	store,
+	cache,
+	createNodeId,
 }) => {
-  if (unstable_shouldOnCreateNode({node})) {
-    let field = "image"
-    let imageUrl = node.customFields[field]
-    if (imageUrl) {
-      let fileNode = await createRemoteFileNode({
-        url: imageUrl, // string that points to the URL of the image
-        parentNodeId: node.id, // id of the parent node of the fileNode you are going to create
-        createNode, // helper function in gatsby-node to generate the node
-        createNodeId, // helper function in gatsby-node to generate the node id
-        cache, // Gatsby's cache
-        store, // Gatsby's redux store
-      })
-      // if the file was created, attach the new node to the parent node
-      if (fileNode) {
-        node.customFields[`${field}LocalImg___NODE`] = fileNode.id
-      }
-    }
-  }
-}
+
+	if (node.properties
+		&& node.properties.referenceName.toLowerCase() === `posts`) {
+		let field = "image"
+		let imageUrl = node.customFields[field]
+		if (imageUrl) {
+			let fileNode = await createRemoteFileNode({
+				url: imageUrl, // string that points to the URL of the image
+				parentNodeId: node.id, // id of the parent node of the fileNode you are going to create
+				createNode, // helper function in gatsby-node to generate the node
+				createNodeId, // helper function in gatsby-node to generate the node id
+				cache, // Gatsby's cache
+				store, // Gatsby's redux store
+			})
+			// if the file was created, attach the new node to the parent node
+			if (fileNode) {
+				node.customFields[`${field}LocalImg___NODE`] = fileNode.id
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/benchmarks/source-cosmicjs/gatsby-node.js b/benchmarks/source-cosmicjs/gatsby-node.js
index 4912615a66686..40ab25a22e39b 100644
--- a/benchmarks/source-cosmicjs/gatsby-node.js
+++ b/benchmarks/source-cosmicjs/gatsby-node.js
@@ -1,15 +1,9 @@
 const kebabCase = require(`lodash.kebabcase`)
 
-function unstable_shouldOnCreateNode({node}) {
-  return node.internal.type === "node__article"
-}
-
-exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
-
 exports.onCreateNode = ({ actions, node }) => {
   const { createNodeField } = actions
 
-  if (unstable_shouldOnCreateNode({node})) {
+  if (node.internal.type === 'node__article') {
     createNodeField({ node, name: "slug", value: kebabCase(node.title) })
   }
 }
@@ -33,13 +27,13 @@ exports.createPages = async ({ actions, graphql, reporter }) => {
     reporter.panicOnBuild(result.errors)
   }
 
-  result.data.articles.edges.map((article) => {
+  result.data.articles.edges.map(article => {
     createPage({
       path: article.node.slug,
       component: require.resolve(`./src/templates/article.js`),
       context: {
         slug: article.node.slug,
-      },
+      }
     })
   })
-}
+}
\ No newline at end of file
diff --git a/benchmarks/source-datocms/gatsby-node.js b/benchmarks/source-datocms/gatsby-node.js
index 4e53a79c06bb2..75f590e92c7a0 100644
--- a/benchmarks/source-datocms/gatsby-node.js
+++ b/benchmarks/source-datocms/gatsby-node.js
@@ -1,15 +1,9 @@
 const kebabCase = require(`lodash.kebabcase`)
 
-function unstable_shouldOnCreateNode({node}) {
-  return node.internal.type === `node__article`
-}
-
-exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
-
 exports.onCreateNode = ({ actions, node }) => {
   const { createNodeField } = actions
 
-  if (unstable_shouldOnCreateNode({node})) {
+  if (node.internal.type === `node__article`) {
     createNodeField({ node, name: `slug`, value: kebabCase(node.title) })
   }
 }
diff --git a/benchmarks/source-drupal/gatsby-node.js b/benchmarks/source-drupal/gatsby-node.js
index ca3007f4bad09..d161fa76d59a7 100644
--- a/benchmarks/source-drupal/gatsby-node.js
+++ b/benchmarks/source-drupal/gatsby-node.js
@@ -1,15 +1,9 @@
 const kebabCase = require(`lodash.kebabcase`)
 
-function unstable_shouldOnCreateNode({node}) {
-  return node.internal.type === `node__article`
-}
-
-exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
-
 exports.onCreateNode = ({ actions, node }) => {
   const { createNodeField } = actions
 
-  if (unstable_shouldOnCreateNode({node})) {
+  if (node.internal.type === "node__article") {
     createNodeField({ node, name: "slug", value: kebabCase(node.title) })
   }
 }
diff --git a/benchmarks/source-flotiq/gatsby-node.js b/benchmarks/source-flotiq/gatsby-node.js
index 7b29474d0da07..26f4f739e91fe 100644
--- a/benchmarks/source-flotiq/gatsby-node.js
+++ b/benchmarks/source-flotiq/gatsby-node.js
@@ -1,15 +1,9 @@
 const kebabCase = require(`lodash.kebabcase`)
 
-function unstable_shouldOnCreateNode({node}) {
-  return node.internal.type === `node__article`
-}
-
-exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
-
 exports.onCreateNode = ({ actions, node }) => {
   const { createNodeField } = actions
 
-  if (unstable_shouldOnCreateNode({node})) {
+  if (node.internal.type === "node__article") {
     createNodeField({ node, name: "slug", value: kebabCase(node.title) })
   }
 }
diff --git a/packages/gatsby-plugin-mdx/gatsby-node.js b/packages/gatsby-plugin-mdx/gatsby-node.js
index 247fbaf343302..e39974ed0a1c9 100644
--- a/packages/gatsby-plugin-mdx/gatsby-node.js
+++ b/packages/gatsby-plugin-mdx/gatsby-node.js
@@ -15,7 +15,7 @@ const {
 exports.sourceNodes = require(`./gatsby/source-nodes`)
 
 /**
- * Check whether the Create Mdx nodes from MDX files.
+ * Check whether to create Mdx nodes from MDX files.
  */
 exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode