adding support for commonJS modules detection

Author: caridy

HISTORY.md

@@ -1,5 +1,12 @@
 Javascript Module Formats Change History
 ========================================
 
-@NEXT@
+0.0.2 (2014-03-05)
 ------------------
+
+* support for `cjs` detection.
+
+0.0.1 (2014-03-05)
+------------------
+
+* first commit/release with support for `amd`, `yui` and `es`.

README.md

@@ -27,12 +27,20 @@ $ npm install js-module-formats
 Usage
 -----
 
-Detect the module format of a file called `file.js`:
+By calling `detect()` with a filesystem path, it returns one of the following values:
+
+* `yui` Modules
+* `amd` Modules
+* `cjs` CommonJS modules (including nodejs modules)
+* `es` Modules
+* `undefined` if the detection fails
+
+To detect the module format of a file called `file.js`:
 
 ```javascript
 var detect = require('js-module-formats').detect,
 
-console.log(detect(__dirname + '/file.js')); // output: `amd` or `yui` or `es` or `undefined`
+console.log(detect(__dirname + '/file.js'));
 ```
 
 **Note:** ES modules without `import` or `export` statements will not be detected.

index.js

@@ -10,14 +10,7 @@
 
 var libfs = require('fs'),
     vm = require('vm'),
-    contextForRunInContext = vm.createContext({
-        require: null,
-        module: null,
-        console: {},
-        window: {},
-        document: {},
-        global: {}
-    });
+    context = vm.createContext({});
 
 module.exports = {
     detect: detect,
@@ -36,7 +29,11 @@ Analyze a javascript file, collecting the module or modules information when pos
 function extract(file) {
     var mods = [];
 
-    contextForRunInContext.YUI = {
+    /**
+    YUI detection is based on a simple rule:
+    - if `YUI.add()` is called
+    **/
+    context.YUI = {
         add: function (name, fn, version, config) {
             mods.push({
                 type: 'yui',
@@ -46,21 +43,61 @@ function extract(file) {
             });
         }
     };
-    contextForRunInContext.define = function (name, fn, version, config) {
+
+
+    /**
+    AMD detection is based on a simple rule:
+    - if `define()` is called
+    **/
+    context.define = function (name, fn, version, config) {
         mods.push({
             type: 'amd',
             name: name,
             version: version,
             config: config
         });
     };
+
+
+    /**
+    CommonJS detection is based on simple rules:
+    -    if the script calls `require()`
+    - or if the script tries to export a function thru `module.exports`
+    - or if the script tries to export an object thru `module.exports`
+    - or if the script tries to export a function thru `exports`
+    - or if the script tries to export an object thru `exports`
+    - or if the script tries to add a new member to `module.exports`
+    **/
+    context.require = function () {
+        mods.push({
+            type: 'cjs'
+        });
+        throw new Error('Common JS script detected');
+    };
+    context.module = {
+        exports: {}
+    };
+    context.exports = context.module.exports;
+
+
+    // executing the content of the file into a new context to avoid leaking
+    // globals during the detection process.
     try {
-        vm.runInContext(libfs.readFileSync(file, 'utf8'), contextForRunInContext, file);
+        vm.runInContext(libfs.readFileSync(file, 'utf8'), context, file);
     } catch (e) {
+        // console.log(e.stack || e);
         // very dummy detection process for ES modules
         if (e.toString() === 'SyntaxError: Unexpected reserved word') {
             mods.push({type: 'es'});
         }
+    } finally {
+        // very dummy detection process for CommonJS modules
+        if (typeof context.module.exports === 'function'
+            || typeof context.exports === 'function'
+            || Object.keys(context.module.exports) > 0
+            || Object.keys(context.exports) > 0) {
+            mods.push({type: 'cjs'});
+        }
     }
     // returning an array when more than one module is defined in the file
     return mods.length > 1 ? mods : mods[0];

package.json

@@ -1,6 +1,6 @@
 {
   "name": "js-module-formats",
-  "version": "0.0.1",
+  "version": "0.0.2",
   "description": "Detect different types of javascript modules formats",
   "homepage": "https://github.com/yahoo/js-module-formats",
   "main": "index",

test/detect.js

@@ -76,4 +76,24 @@ describe('detect', function () {
 
     });
 
+    describe('cjs', function () {
+
+        it('should detect `cjs` for fixtures/cjs.js', function () {
+            expect(detect(fixtures + 'cjs.js')).to.be.equal('cjs');
+        });
+
+        it('should detect `cjs` for fixtures/cjs-require.js', function () {
+            expect(detect(fixtures + 'cjs-require.js')).to.be.equal('cjs');
+        });
+
+        it('should detect `cjs` for fixtures/cjs-exports.js', function () {
+            expect(detect(fixtures + 'cjs.js')).to.be.equal('cjs');
+        });
+
+        it('should detect `cjs` for fixtures/cjs-module-exports.js', function () {
+            expect(detect(fixtures + 'cjs.js')).to.be.equal('cjs');
+        });
+
+    });
+
 });

test/fixtures/cjs-exports.js

@@ -0,0 +1,3 @@
+exports = function () {
+	return true;
+};

test/fixtures/cjs-module-exports.js

@@ -0,0 +1,3 @@
+module.exports = function () {
+	return true;
+};

test/fixtures/cjs-require.js

@@ -0,0 +1 @@
+var path = require('path');

test/fixtures/cjs.js

@@ -0,0 +1,2 @@
+var path = require('path');
+module.exports = path;