Merge pull request #7 from iambumblehead/add-caching

added caching, small update to README

README.md

@@ -2,24 +2,27 @@ resolvewithplus
 ===============
 [![npm version](https://badge.fury.io/js/resolvewithplus.svg)](https://badge.fury.io/js/resolvewithplus) [![Build Status](https://github.com/iambumblehead/resolvewithplus/workflows/nodejs-ci/badge.svg)][2]
 
-_resolvewithplus_ is an iteration of the _resolvewith_ package, which resolves CJS modules following [the original node.js spec.][2] _resolvewithplus_ is changed to an ESM module and adds support for ESM-style `import 'name'` resolutions. When packages export both ESM and CJS, `resolvewithplus` will return the ESM path. Resolving ESM paths is complex and ESM support will be lacking for edge-cases.
+_resolvewithplus_ iterates on the _resolvewith_ package for resolving CJS modules following [the original node.js spec.][2] _resolvewithplus_ is changed to an ESM module and adds support for ESM `import 'name'` resolutions.
 
-```javascript
-// CJS
-resolvewithplus('./testfiles/testscript.js', '/Users/bumble/resolvewith/test/')
-// '/Users/bumble/resolvewith/test/testfiles/testscript.js'
-resolvewithplus('testmodule', '/Users/bumble/resolvewith/test/')
-// '/Users/bumble/resolvewith/node_modules/testmodule/index.js'
+When a package exports both ESM and CJS, `resolvewithplus` returns the ESM path (tries to). Resolving ESM paths is complex and ESM support will be lacking for edge-cases.
 
-// ESM paths are returned by default and not CJS paths
+```javascript
+// ESM paths are returned by default rather than CJS paths
 resolvewithplus('koa', '/Users/bumble/resolvewith/test/');
 // '/Users/bumble/resolvewith/node_modules/koa/dist/koa.mjs'
 
+// A CJS path is returned when the ESM path is not found
+resolvewithplus('./testfiles/testscript.js', '/Users/bumble/resolvewith/test/')
+// '/Users/bumble/resolvewith/test/testfiles/testscript.js'
+
 // use the older 'resolvewith' package to resolve CJS paths
 resolvewith('koa', '/Users/bumble/resolvewith/test/');
 // '/Users/bumble/resolvewith/node_modules/koa/lib/application.js'
 ```
 
+_resolvewithplus_ caches and reuse results it generates. The first call follows rules to locate the file. Subsequent calls using the values return reults from a key store.
+
+
 [0]: http://www.bumblehead.com                            "bumblehead"
 [1]: https://github.com/iambumblehead/resolvewith/blob/master/src/resolvewith.js
 [2]: https://nodejs.org/api/modules.html#modules_module_require_id

package.json

@@ -1,6 +1,6 @@
 {
   "name": "resolvewithplus",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "license": "MIT",
   "main": "resolvewithplus.mjs",
   "readmeFilename": "README.md",

resolvewithplus.mjs

@@ -5,8 +5,16 @@ import module from 'module';
 const require = module.createRequire(import.meta.url);
 
 export default (o => {
-  o = (requirepath, withpath, opts) =>
-    o.begin(requirepath, withpath, opts || {});
+  o = (requirepath, withpath, opts) => {
+    let resolvedpath = o.cache[requirepath+withpath];
+    if (resolvedpath) return resolvedpath;
+
+    resolvedpath = o.begin(requirepath, withpath, opts || {});
+
+    return o.cache[requirepath+withpath] = resolvedpath;
+  };
+
+  o.cache = {};
 
   // https://nodejs.org/api/modules.html#modules_module_require_id
   //
@@ -45,8 +53,9 @@ export default (o => {
 
   o.iscoremodule = p => {
     try {
-      return p === require.resolve(p) &&
-        !(p.includes(path.sep) && path.existsSync(p));
+      return !/^[/.]/.test(p)
+        && p === require.resolve(p)
+        && !(p.includes(path.sep) && path.existsSync(p));
     } catch (e) {
       return false;
     }

resolvewithplus.spec.mjs

@@ -82,3 +82,9 @@ test('should handle package.json "exports" field', t => {
     resolvewithplus('koa', fullpath, { esm : true }),
     path.resolve('./node_modules/koa/dist/koa.mjs'));
 });
+
+test('should return values from cache', t => {
+  resolvewithplus.cache['filepathkey'] = 'filepathvalue';
+
+  t.is(resolvewithplus('filepath', 'key'), 'filepathvalue');
+});