feat: add decorator option to preprocessor function

README.md

@@ -32,7 +32,7 @@ module.exports = (on) => {
 
 ## Options
 
-Pass in options as the second argument to `browserify`:
+Pass in options as the first argument to `browserify`:
 
 ```javascript
 module.exports = (on) => {
@@ -164,6 +164,28 @@ module.exports = (on) => {
 }
 ```
 
+## Decoratoring the Browserify instance
+
+Pass in a decorator function as the second argument to `browserify`:
+
+```javascript
+module.exports = (on) => {
+  const options = {
+    // options here
+  }
+
+  const decorator = (b) => {
+    // b is the instance of Browserify.
+    // You can call any of the [methods](https://github.com/browserify/browserify#methods)
+    // on b that you need in order to further customize Browserify
+    b.ignoreFile('module-to-ignore')
+  };
+
+  on('file:preprocessor', browserify(options, decorator))
+}
+```
+
+
 ## Contributing
 
 Run all tests once:

index.js

@@ -91,7 +91,9 @@ const getBrowserifyOptions = (entry, userBrowserifyOptions = {}) => {
 //
 // on('file:preprocessor', browserify(options))
 //
-const preprocessor = (options = {}) => {
+// the decorator function will be called with the Browserify instance
+//
+const preprocessor = (options = {}, decorator = undefined) => {
   debug('received user options: %o', options)
 
   // we return function that accepts the arguments provided by
@@ -132,6 +134,10 @@ const preprocessor = (options = {}) => {
 
     const bundler = browserify(browserifyOptions)
 
+    if (decorator) {
+      decorator(bundler)
+    }
+
     if (file.shouldWatch) {
       debug('watching')
       bundler.plugin(watchify, watchifyOptions)

test/unit/index_spec.js

@@ -58,8 +58,8 @@ describe('browserify preprocessor', function () {
       emit: sandbox.spy(),
     }
 
-    this.run = () => {
-      return preprocessor(this.options)(this.file)
+    this.run = (decorator) => {
+      return preprocessor(this.options, decorator)(this.file)
     }
   })
 
@@ -90,6 +90,16 @@ describe('browserify preprocessor', function () {
         })
       })
 
+      it('browserify can be decorated', function () {
+        const decorator = sandbox.spy();
+
+        return this.run(decorator).then(() => {
+          expect(browserify).to.be.called
+          expect(decorator).to.be.called
+        })
+
+      });
+
       it('returns existing bundle if called again with same filePath', function () {
         browserify.reset()
         browserify.returns(this.bundlerApi)