thlorenz/browserify-shim

browserify-shim

Make CommonJS-Incompatible Files Browserifyable

package.json

{
  "main": "./js/entry.js",
  "browser": {
    "jquery": "./js/vendor/jquery.js"
  },
  "browserify-shim": {
    "jquery": "$",
    "three": "global:THREE"
  },
  "browserify": {
    "transform": [ "browserify-shim" ]
  },
  "dependencies": {
    "browserify-shim": "~3.2.0"
  }
}

browserify . -d -o bundle.js

Table of Contents generated with DocToc

• Installation
• Features
• API
  • You Will Always
    • 1. Install browserify-shim dependency
    • 2. Register browserify-shim as a transform with browserify
    • 3. Provide browserify-shim config
      • Short Form vs. Long Form config
  • You will sometimes
    • a) Expose global variables via global:*
      • 1. add script tag for library you want to expose
      • 2. Add expose global config to package.json
      • 2.a. Add expose global config to external shim config
      • 3. Require library by the name it was exposed as
      • Why not just var THREE = window.THREE?
    • b) Use aliases
    • c) Provide an external shim config
    • d) Diagnose what browserify-shim is doing
• Multi Shim Example including dependencies
  • a) Config inside package.json without aliases
  • b) Config inside package.json with aliases
  • c) Config inside ./config/shim.js without aliases
    • package.json
    • shim.js
• More Examples

Installation

npm install browserify browserify-shim

For a version compatible with [email protected] run npm install [email protected] instead.

For a version compatible with the v2 API npm install [email protected] instead.

Features

The core features of browserify-shim are:

• Shims non-CommonJS modules in order for them to be browserified by specifying an alias, the path to the file, and the identifier under which the module attaches itself to the global window object.
• Includes depends for shimming libraries that depend on other libraries being in the global namespace.
• applies shims configured inside the dependencies of your package

Additionally, it handles the following real-world edge cases:

• Modules that just declare a var foo = ... on the script level and assume it gets attached to the window object. Since the only way they will ever be run is in the global context — "ahem, … NO?!"
• Makes define and also module be undefined, in order to fix improperly-authored libraries that need shimming but try anyway to use AMD or CommonJS. For more info read the comment inside this fixture
• removes invalid requires, i.e. require('jquery') although 'jquery' isn't installed due to the library being improperly published or installed incorrectly via a downloader like bower

Since browserify-shim is a proper browserify transform you can publish packages with files that need to be shimmed, granted that you specify the shim config inside the package.json.

When browserify resolves your package it will run the browserify-shim transform and thus shim what's necessary when generating the bundle.

browserify-shim walks upwards from each source file and uses the first "browserify-shim" configuration it finds in a package.json file. You can't shim files outside your project from your project's package. You can add multiple package.json files as long as browserify-shim can always find a package above each source file with the right configuration.

API

You Will Always

1. Install browserify-shim dependency

In most cases you want to install it as a devDependency via:

npm install -D browserify-shim

2. Register browserify-shim as a transform with browserify

Inside package.json add:

{ 
  "browserify": {
    "transform": [ "browserify-shim" ]
  }
}

Browserify transforms are run in order and may modify your source code along the way. You'll typically want to include browserify-shim last.

3. Provide browserify-shim config

Inside package.json add:

{
  "browserify-shim": {
    "./js/vendor/jquery.js": "$",
    "three": "global:THREE"
  }
}

The above includes ./js/vendor/jquery.js (relative to the package.json) in the bundle and exports window.$.

Additionally it exposes window.THREE as three, so you can var three = require('three'). More info below.

Short Form vs. Long Form config

Since jquery does not depend on other shimmed modules and thus has no depends field, we used the short form to specify its exports, however the example above is equivalent to:

{
  "browserify-shim": {
    "./js/vendor/jquery.js": { "exports": "$" }
  }
}

You will sometimes

a) Expose global variables via global:*

In some cases the libraries you are using are very large and you'd prefer to add them via a script tag instead to get the following benefits:

• faster bundling times since the library is not included in the bundle
• pull libraries from a CDN which allows it to be pulled straight from the user's browser cache in case it was downloaded before

We'll show how this works by taking the rather huge yet awesome THREE.js library as an example:

1. add script tag for library you want to expose

<!-- index.html -->
<head>
  <meta charset=utf-8 />
  <script type="text/javascript" src="http://cdnjs.cloudflare.com/ajax/libs/three.js/r61/three.min.js"></script>
</head>

2. Add expose global config to package.json

{
  "browserify-shim": {
    "three": "global:THREE"
  }
}

2.a. Add expose global config to external shim config

In case you are using an external shim config, you may achieve the same by specifying the global via an exports.

module.exports = {
  'three': { exports: 'global:THREE' }
}

more about external configs here

Note: THREE.js attaches window.THREE.

3. Require library by the name it was exposed as

var THREE = require('three');

Why not just var THREE = window.THREE?

You want to avoid spreading the knowledge that THREE is a global and stay consistent in how you resolve dependencies. Additionally if THREE would ever be published to npm and you decide to install it from there, you don't have to change any of your code since it already is requireing it properly.

b) Use aliases

You may expose files under a different name via the browser field and refer to them under that alias in the shim config:

{
  "browser": {
    "jquery": "./js/vendor/jquery.js"
  },
  "browserify-shim": {
    "jquery": "$"
  }
}

This also allows you to require this module under the alias, i.e.: var $ = require('jquery').

c) Provide an external shim config

{
  "browserify-shim": "./config/shim.js"
}

The external shim format is very similar to the way in which the shim is specified inside the package.json. See below for more details.

d) Diagnose what browserify-shim is doing

You may encounter problems when your shim config isn't properly setup. In that case you can diagnose them via the BROWSERIFYSHIM_DIAGNOSTICS flag.

Simply set the flag when building your bundle, i.e.:

BROWSERIFYSHIM_DIAGNOSTICS=1 browserify -d . -o js/bundle.js

or in a build.js script add: process.env.BROWSERIFYSHIM_DIAGNOSTICS=1 to the top.

Multi Shim Example including dependencies

Some libraries depend on other libraries to have attached their exports to the window for historical reasons :(. (Hopefully soon we can truly say that this bad design is history.)

In this contrived example we are shimming four libraries since none of them are commonJS compatible:

• x exports window.$
• x-ui exports nothing since it just attaches itself to x. Therefore x-ui depends on x.
• y exports window.Y and also depends on x expecting to find it on the window as $.
• z exports window.zorro and depends on x and y. It expects to find x on the window as $, but y on the window as YNOT, which is actually different than the name under which y exports itself.

We will be using the depends field in order to ensure that a dependency is included and initialized before a library that depends on it is initialized.

Below are three examples, each showing a way to properly shim the above mentioned modules.

a) Config inside package.json without aliases

{
  "browserify": {
    "transform": [ "browserify-shim" ]
  },
  "browserify-shim": {
    "./vendor/x.js"    :  "$",
    "./vendor/x-ui.js" :  { "depends": [ "./vendor/x.js" ] },
    "./vendor/y.js"    :  { "exports": "Y", "depends": [ "./vendor/x.js:$" ] },
    "./vendor/z.js"    :  { "exports": "zorro", "depends": [ "./vendor/x.js:$", "./vendor/y.js:YNOT" ] }
  }
}

Note: the depends array consists of entries of the format path-to-file:export

b) Config inside package.json with aliases

{
  "browserify": {
    "transform": [ "browserify-shim" ]
  },
  "browser": {
    "x"    :  "./vendor/x.js",
    "x-ui" :  "./vendor/x-ui.js",
    "y"    :  "./vendor/y.js",
    "z"    :  "./vendor/z.js"
  },
   "browserify-shim": {
    "x"    :  "$",
    "x-ui" :  { "depends": [ "x" ] },
    "y"    :  { "exports": "Y", "depends": [ "x:$" ] },
    "z"    :  { "exports": "zorro", "depends": [ "x:$", "y:YNOT" ] }
  }
}

Note: the depends entries make use of the aliases as well alias:export

c) Config inside ./config/shim.js without aliases

package.json

{
  "browserify": {
    "transform": [ "browserify-shim" ]
  },
  "browserify-shim": "./config/shim.js"
}

shim.js

module.exports = {
  '../vendor/x.js'    :  { 'exports': '$' },
  '../vendor/x-ui.js' :  { 'depends': { '../vendor/x.js': null } },
  '../vendor/y.js'    :  { 'exports': 'Y', 'depends': { '../vendor/x.js': '$' } },
  '../vendor/z.js'    :  { 'exports': 'zorro', 'depends': { '../vendor/x.js': '$', '../vendor/y.js': 'YNOT' } }
}

Note: all paths are relative to ./config/shim.js instead of the package.json.

The main difference to a) is the depends field specification. Instead it being an array of strings it expresses its dependencies as a hashmap:

• key: path-to-file
• value: the name under which it is expected to be attached on the window

More Examples

• shim-jquery
• expose-jquery
• shim-jquery-external
• the tests are a great resource to investigate the different ways to configure shims and to understand how shims are applied to packages found inside the node_modules of your package