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This repository formalizes the design and implementation of the Universal Module Definition (UMD) API for JavaScript modules. These are modules which are capable of working everywhere, be it in the client, on the server or elsewhere.

The UMD pattern typically attempts to offer compatibility with the most popular script loaders of the day (e.g RequireJS amongst others). The repository aims to formalize thedefinition ofuniversal modules. It does not provide auniversal definition. The standard was written at the time because everyone defined their universal modules differently - there were some common approaches, with varying support for different environments, but nothing really established.

A universal module, as already noted, works in multiple environments. Before universal modules, libraries would distribute separate files for the different environments, e.g.library.amd.js,library.common.js andlibrary.global.js. This was a hassle for maintainers, since it required the usage of a build tool (which JavaScriptdoes did generally not need) and extra documentation. So the aim was to define a universal module, a single file, which was all that was needed for the author to write and distribute and for the user to (down)load. Notice this was before package managers and repositories were common (or: when they started to become more popular, and you had to change your library into a module to support them).

Yet, there were still variations. Modules written for web browsers did not need to consider supporting the commonjs format, as they wouldn't work in Node.JS anyway. Modules that had no dependencies wouldn't need a UMD pattern that supportedrequire. Modules that did not use circular dependencies wouldn't need a pattern that supports a mutableexports object. You can find the explanation of these differences, and their trade-offs, in the comments documenting the patterns below. A library author can read through them and pick the right one for their supported environments.

In many cases, UMD usesAMD as a base, with special-casing added to handleCommonJS compatibility.

• amdWeb.js -Defines a module that works with AMD and browser globals. If you also wantto export a global even when AMD is in play (useful if you are loading otherscripts that still expect that global), useamdWebGlobal.js.
• returnExports.js -Defines a module that works in Node, AMD and browser globals. If you also wantto export a global even when AMD is in play (useful if you are loading otherscripts that still expect that global), usereturnExportsGlobal.js.
• commonjsStrict.js -Defines a module that works with more CommonJS runtimes, and for modules thatwill have a circular dependency. If you also wantto export a global even when AMD is in play (useful if you are loading otherscripts that still expect that global), usecommonjsStrictGlobal.js

• jqueryPlugin.js -Defines a jQuery plugin that works with AMD and browser globals.

These are useful for using AMD style while still making modules that can beused in Node and installed via npm without extra dependencies to set up thefull AMD API.

This approach does not allow the use ofAMD loader plugins,just basic JS module dependencies. It also does not support thecallback-style require thatis usable in AMD.

• nodeAdapter.js -Best for when using AMD style but want it to work in Node without a helper librarythat sets up AMD.
• commonjsAdapter.js -Similar to nodeAdapter.js, but compatible with more CommonJS runtimes, and ifyou want to define a circular dependency.

• docpad-plugin-umd is aDocPad plugin for surrounding JavaScript code with UMD boilerplate
• grunt-umd is aGrunt task for surrounding JavaScript code with UMD boilerplate
• gulp-umd is aGulp task for surrounding JavaScript code with UMD boilerplate
• grunt-urequire is a Grunt wrapper foruRequire a conversion tool for universal JavaScript modules.
• generator-umd is an Yeoman Generator that creates a single module project with UMD boilerplate

• Unit testing UMD with grunt-contrib-jasmine

• Browserify and the Universal Module Definition

• noConflict. Although with AMD loaders and build tools, it should be possible to get version specific bindings,maybe show a version that has a noConflict option.
• Variation with attaching some functionality to a $ impersonator. Although, it istempting to say for that case, ask for 'jquery' as a dependency, and if the developerwants to use something different than the actual 'jquery', map that file to the 'jquery' name.That is one of the strengths of module names, they can be mapped to different implementations.
• Usage examples
  • Further justifications for usage
  • Gotchas/custom-tweaks we're aware of, but would rather not apply to the default UMD boilerplate

The basic pattern for the UMD variations in this repository was derived from the approach@kriskowal used for theQ promise library.

Earlier UMD variations were also of influence, ranging from Kit-Cambridge'sUMD, through topatterns discussed by Addy Osmani, Thomas Davis and Ryan Florence and most recently the UMD patterns proposed byJames Burke.

Copyright (c) the UMD contributors

Licensed under theMIT License.