Merge commit '9af485a584e47fd503ed5c62b9f6482574715f1e' as 'thirdparty/systemjs'

1 files changed, 84 insertions, 0 deletions

diff --git a/thirdparty/systemjs/docs/creating-plugins.md b/thirdparty/systemjs/docs/creating-plugins.md
new file mode 100644
index 000000000..531ece163
--- /dev/null
+++ b/thirdparty/systemjs/docs/creating-plugins.md
@@ -0,0 +1,84 @@
+### Creating a Plugin
+
+A plugin is just a set of overrides for the loader hooks of the ES6 module specification.
+
+The hooks plugins can override are `locate`, `fetch`, `translate` and `instantiate`.
+
+Read more about loader extensions and hooks at the [ES6 Module Loader polyfill wiki](https://github.com/ModuleLoader/es6-module-loader/blob/v0.17.0/docs/loader-extensions.md).
+
+The behaviors of the hooks are:
+
+* Locate: Overrides the location of the plugin resource
+* Fetch: Called with third argument representing default fetch function, has full control of fetch output.
+* Translate: Returns the translated source from `load.source`, can also set `load.metadata.sourceMap` for full source maps support.
+* Instantiate: Providing this hook as a promise or function allows the plugin to hook instantiate. Any return value becomes the defined custom module object for the plugin call.
+
+### Building Plugins
+
+When building via [SystemJS Builder](https://github.com/systemjs/builder), plugins that use the translate hook will be inlined into the bundle automatically.
+
+In this way, the bundle file becomes independent of the plugin loader and resource.
+
+If it is desired for the plugin itself not to be inlined into the bundle in this way, setting `exports.build = false` on the plugin will disable this,
+causing the plugin loader itself to be bundled in production instead to continue to dynamically load the resource.
+
+#### Sample CoffeeScript Plugin
+
+For example, we can write a CoffeeScript plugin with the following (CommonJS as an example, any module format works fine):
+
+js/coffee.js:
+```javascript
+  var CoffeeScript = require('coffeescript');
+
+  exports.translate = function(load) {
+    // optionally also set the sourceMap to support both builds and in-browser transpilation
+    // load.metadata.sourceMap = generatedSourceMap;
+    return CoffeeScript.compile(load.source);
+  }
+```
+
+By overriding the `translate` hook, we now support CoffeeScript loading with:
+
+```
+ - js/
+   - coffee.js             our plugin above
+   - coffeescript.js       the CoffeeScript compiler
+ - app/
+   - main.coffee
+```
+
+```javascript
+  System.import('app/main.coffee!').then(function(main) {
+    // main is now loaded from CoffeeScript
+  });
+```
+
+Source maps can also be passed by setting `load.metadata.sourceMap`.
+
+#### Sample CSS Plugin
+
+A CSS plugin, on the other hand, could override the fetch hook:
+
+js/css.js:
+```javascript
+  exports.fetch = function(load, fetch) {
+    return new Promise(function(resolve, reject) {
+      var cssFile = load.address;
+
+      var link = document.createElement('link');
+      link.rel = 'stylesheet';
+      link.href = cssFile;
+      link.onload = resolve;
+
+      document.head.appendChild(link);
+    })
+    .then(function() {
+      // return an empty module in the module pipeline itself
+      return '';
+    });
+  }
+```
+
+Each loader hook can either return directly or return a promise for the value.
+
+The other loader hooks are also treated otherwise identically to the specification.