diff --git a/.eslintrc-frontend.yml b/.eslintrc-frontend.yml
index 9cec4789c3513..7fcc1ead4807a 100644
--- a/.eslintrc-frontend.yml
+++ b/.eslintrc-frontend.yml
@@ -9,7 +9,7 @@ parserOptions:
 extends:
   - "standard-jsx"
   - "standard-react"
-  - "./.eslintrc-preferred.yml"
+  - "./.eslintrc.yml"
 
 settings:
   react:
diff --git a/.eslintrc-preferred.yml b/.eslintrc-preferred.yml
deleted file mode 100644
index f08d82881046f..0000000000000
--- a/.eslintrc-preferred.yml
+++ /dev/null
@@ -1,29 +0,0 @@
-plugins:
-  - "chai-friendly"
-
-extends:
-  - "standard"
-  - "prettier"
-
-parserOptions:
-  # Override eslint-config-standard, which incorrectly sets this to "module",
-  # though that setting is only for ES6 modules, not CommonJS modules.
-  sourceType: "script"
-
-rules:
-  # These are not disabled by eslint-config-prettier
-  spaced-comment: "off"
-  standard/object-curly-even-spacing: "off"
-  one-var: "off"
-
-  # Shields additions.
-  no-var: "error"
-  prefer-const: "error"
-  strict: "error"
-  arrow-body-style: ["error", "as-needed"]
-
-  # Chai friendly.
-  no-unused-expressions: "off"
-  chai-friendly/no-unused-expressions: "error"
-
-  mocha/prefer-arrow-callback: "error"
diff --git a/.eslintrc.yml b/.eslintrc.yml
index 6a09b28ea259f..240cf97eaf3ce 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -1,19 +1,19 @@
-parserOptions:
-  ecmaVersion: 8
+extends:
+  - standard
+  - prettier
 
 env:
   node: true
-  # We use Promise, Map, and occasional ES6 syntax.
-  es6: true
   mocha: true
 
+parserOptions:
+  # Override eslint-config-standard, which incorrectly sets this to "module",
+  # though that setting is only for ES6 modules, not CommonJS modules.
+  sourceType: "script"
+
 plugins:
   - mocha
-
-extends:
-  # Enable a set of unopinionated, style-agnostic rules which cover many
-  # likely errors.
-  - "eslint:recommended"
+  - "chai-friendly"
 
 rules:
   # Disable some rules from eslint:recommended.
@@ -23,14 +23,22 @@ rules:
   # what the functions are doing.
   no-unused-vars: ["error", {"args": "none"}]
 
-  # We use semicolons.
-  semi: ["error", "always"]
+  # These should be disabled by eslint-config-prettier, but are not.
+  spaced-comment: "off"
+  standard/object-curly-even-spacing: "off"
+  one-var: "off"
 
-  # We keep whitespace cleaned up.
-  no-trailing-spaces: "error"
-  eol-last: "error"
-  object-curly-spacing: ["error", "always"]
-  comma-dangle: ["error", "always-multiline"]
+  # Shields additions.
+  no-var: "error"
+  prefer-const: "error"
+  strict: "error"
+  arrow-body-style: ["error", "as-needed"]
 
+  # Mocha-related.
   mocha/no-exclusive-tests: "error"
   mocha/no-mocha-arrows: "error"
+  mocha/prefer-arrow-callback: "error"
+
+  # Chai friendly.
+  no-unused-expressions: "off"
+  chai-friendly/no-unused-expressions: "error"
diff --git a/dangerfile.js b/dangerfile.js
index d2f8f934727fe..4722810c502e3 100644
--- a/dangerfile.js
+++ b/dangerfile.js
@@ -1,3 +1,5 @@
+'use strict'
+
 // Have you identified a contributing guideline that should be included here?
 // Please open a pull request!
 //
@@ -43,7 +45,7 @@ message([
   `@${danger.github.pr.user.login}!`,
 ].join(''));
 
-if (targetBranch != 'master') {
+if (targetBranch !== 'master') {
   const message = `This PR targets \`${targetBranch}\``;
   const idea = 'It is likely that the target branch should be `master`';
   warn(`${message} - <i>${idea}</i>`);
@@ -99,10 +101,10 @@ if (capitals.created || underscores.created) {
   ].join(''));
 }
 
-const all_files = danger.git.created_files.concat(danger.git.modified_files);
+const allFiles = danger.git.created_files.concat(danger.git.modified_files);
 
-all_files.forEach(function(file) {
-  danger.git.diffForFile(file).then(function(diff) {
+allFiles.forEach(file => {
+  danger.git.diffForFile(file).then(diff => {
     if (/\+.*assert[(.]/.test(diff.diff)) {
       warn([
         `Found 'assert' statement added in \`${file}\`. <br>`,
@@ -117,23 +119,23 @@ function onlyUnique(value, index, self) {
   return self.indexOf(value) === index;
 }
 
-const affectedServices = all_files
-  .map(function(file) {
+const affectedServices = allFiles
+  .map(file => {
     const match = file.match(/^services\/(.+)\/.+\.service.js$/);
     return match ? match[1] : undefined;
   })
   .filter(Boolean)
   .filter(onlyUnique);
 
-const testedServices = all_files
-  .map(function(file) {
+const testedServices = allFiles
+  .map(file => {
     const match = file.match(/^services\/(.+)\/.+\.tester.js$/);
     return match ? match[1] : undefined;
   })
   .filter(Boolean)
   .filter(onlyUnique);
 
-affectedServices.forEach(function(service) {
+affectedServices.forEach(service => {
   if (testedServices.indexOf(service) === -1) {
     warn(
       [
diff --git a/lib/.eslintrc.yml b/lib/.eslintrc.yml
deleted file mode 100644
index 22fe798e18073..0000000000000
--- a/lib/.eslintrc.yml
+++ /dev/null
@@ -1 +0,0 @@
-extends: '../.eslintrc-preferred.yml'
diff --git a/next.config.js b/next.config.js
index 8164bee263f78..0254924c5eddb 100644
--- a/next.config.js
+++ b/next.config.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const envFlag = require('node-env-flag');
 const webpack = require('webpack');
 const shouldAnalyze = envFlag(process.env.ANALYZE);
diff --git a/server.js b/server.js
index a55c4e339aa1c..5fc2c48d3b431 100644
--- a/server.js
+++ b/server.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const dom = require('xmldom').DOMParser;
+const { DOMParser } = require('xmldom');
 const jp = require('jsonpath');
 const path = require('path');
 const xpath = require('xpath');
@@ -95,9 +95,9 @@ githubConstellation.initialize(camp);
 
 suggest.setRoutes(config.cors.allowedOrigin, githubApiProvider, camp);
 
-camp.notfound(/\.(svg|png|gif|jpg|json)/, function(query, match, end, request) {
-    var format = match[1];
-    var badgeData = getBadgeData("404", query);
+camp.notfound(/\.(svg|png|gif|jpg|json)/, (query, match, end, request) => {
+    const format = match[1];
+    const badgeData = getBadgeData("404", query);
     badgeData.text[1] = 'badge not found';
     badgeData.colorscheme = 'red';
     // Add format to badge data.
@@ -106,7 +106,7 @@ camp.notfound(/\.(svg|png|gif|jpg|json)/, function(query, match, end, request) {
     makeSend(format, request.res, end)(svg);
 });
 
-camp.notfound(/.*/, function(query, match, end, request) {
+camp.notfound(/.*/, (query, match, end, request) => {
   end(null, { template: '404.html' });
 });
 
@@ -122,14 +122,14 @@ camp.route(/^\/badge\/dynamic\/(json|xml|yaml)\.(svg|png|gif|jpg|json)$/,
 cache({
   queryParams: ['uri', 'url', 'query', 'prefix', 'suffix'],
   handler: function(query, match, sendBadge, request) {
-    var type = match[1];
-    var format = match[2];
-    var prefix = query.prefix || '';
-    var suffix = query.suffix || '';
-    var pathExpression = query.query;
-    var requestOptions = {};
+    const type = match[1];
+    const format = match[2];
+    const prefix = query.prefix || '';
+    const suffix = query.suffix || '';
+    const pathExpression = query.query;
+    let requestOptions = {};
 
-    var badgeData = getBadgeData('custom badge', query);
+    const badgeData = getBadgeData('custom badge', query);
 
     if (!query.uri && !query.url || !query.query){
       setBadgeColor(badgeData, 'red');
@@ -138,8 +138,9 @@ cache({
       return;
     }
 
+    let url
     try {
-      var url = encodeURI(decodeURIComponent(query.url || query.uri));
+      url = encodeURI(decodeURIComponent(query.url || query.uri));
     } catch(e){
       setBadgeColor(badgeData, 'red');
       badgeData.text[1] = 'malformed url';
@@ -183,18 +184,18 @@ cache({
         let innerText = [];
         switch (type){
           case 'json':
-            data = (typeof data == 'object' ? data : JSON.parse(data));
+            data = (typeof data === 'object' ? data : JSON.parse(data));
             data = jp.query(data, pathExpression);
             if (!data.length) {
-              throw 'no result';
+              throw Error('no result');
             }
             innerText = data;
             break;
           case 'xml':
-            data = new dom().parseFromString(data);
+            data = new DOMParser().parseFromString(data);
             data = xpath.select(pathExpression, data);
             if (!data.length) {
-              throw 'no result';
+              throw Error('no result');
             }
             data.forEach((i,v)=>{
               innerText.push(pathExpression.indexOf('@') + 1 ? i.value : i.firstChild.data);
@@ -204,7 +205,7 @@ cache({
             data = yaml.safeLoad(data);
             data = jp.query(data, pathExpression);
             if (!data.length) {
-              throw 'no result';
+              throw Error('no result');
             }
             innerText = data;
             break;
@@ -212,7 +213,7 @@ cache({
         badgeData.text[1] = (prefix || '') + innerText.join(', ') + (suffix || '');
       } catch (e) {
         setBadgeColor(badgeData, 'lightgrey');
-        badgeData.text[1] = e;
+        badgeData.text[1] = e.message;
       } finally {
         sendBadge(format, badgeData);
       }
@@ -222,16 +223,16 @@ cache({
 
 // Any badge.
 camp.route(/^\/(:|badge\/)(([^-]|--)*?)-?(([^-]|--)*)-(([^-]|--)+)\.(svg|png|gif|jpg)$/,
-function(data, match, end, ask) {
-  var subject = escapeFormat(match[2]);
-  var status = escapeFormat(match[4]);
-  var color = escapeFormat(match[6]);
-  var format = match[8];
+(data, match, end, ask) => {
+  const subject = escapeFormat(match[2]);
+  const status = escapeFormat(match[4]);
+  const color = escapeFormat(match[6]);
+  const format = match[8];
 
   analytics.noteRequest(data, match);
 
   // Cache management - the badge is constant.
-  var cacheDuration = (3600*24*1)|0;    // 1 day.
+  const cacheDuration = (3600*24*1)|0;    // 1 day.
   ask.res.setHeader('Cache-Control', 'max-age=' + cacheDuration);
   if (+(new Date(ask.req.headers['if-modified-since'])) >= +serverStartTime) {
     ask.res.statusCode = 304;
@@ -242,7 +243,7 @@ function(data, match, end, ask) {
 
   // Badge creation.
   try {
-    var badgeData = getBadgeData(subject, data);
+    const badgeData = getBadgeData(subject, data);
     badgeData.text[0] = getLabel(subject, data);
     badgeData.text[1] = status;
     badgeData.colorB = makeColorB(color, data);
@@ -264,13 +265,13 @@ function(data, match, end, ask) {
 
 // Production cache debugging.
 let bitFlip = false;
-camp.route(/^\/flip\.svg$/, function(data, match, end, ask) {
-  var cacheSecs = 60;
+camp.route(/^\/flip\.svg$/, (data, match, end, ask) => {
+  const cacheSecs = 60;
   ask.res.setHeader('Cache-Control', 'max-age=' + cacheSecs);
-  var reqTime = new Date();
-  var date = (new Date(+reqTime + cacheSecs * 1000)).toGMTString();
+  const reqTime = new Date();
+  const date = (new Date(+reqTime + cacheSecs * 1000)).toGMTString();
   ask.res.setHeader('Expires', date);
-  var badgeData = getBadgeData('flip', data);
+  const badgeData = getBadgeData('flip', data);
   bitFlip = !bitFlip;
   badgeData.text[1] = bitFlip? 'on': 'off';
   badgeData.colorscheme = bitFlip? 'brightgreen': 'red';
@@ -280,13 +281,13 @@ camp.route(/^\/flip\.svg$/, function(data, match, end, ask) {
 
 // Any badge, old version.
 camp.route(/^\/([^/]+)\/(.+).png$/,
-function(data, match, end, ask) {
-  var subject = match[1];
-  var status = match[2];
-  var color = data.color;
+(data, match, end, ask) => {
+  const subject = match[1];
+  const status = match[2];
+  const color = data.color;
 
   // Cache management - the badge is constant.
-  var cacheDuration = (3600*24*1)|0;    // 1 day.
+  const cacheDuration = (3600*24*1)|0;    // 1 day.
   ask.res.setHeader('Cache-Control', 'max-age=' + cacheDuration);
   if (+(new Date(ask.req.headers['if-modified-since'])) >= +serverStartTime) {
     ask.res.statusCode = 304;
@@ -297,7 +298,7 @@ function(data, match, end, ask) {
 
   // Badge creation.
   try {
-    var badgeData = { text: [subject, status] };
+    const badgeData = { text: [subject, status] };
     badgeData.colorscheme = color;
     const svg = makeBadge(badgeData);
     makeSend('png', ask.res, end)(svg);
diff --git a/services/.eslintrc.yml b/services/.eslintrc.yml
deleted file mode 100644
index 22fe798e18073..0000000000000
--- a/services/.eslintrc.yml
+++ /dev/null
@@ -1 +0,0 @@
-extends: '../.eslintrc-preferred.yml'