systemjs-plugin-traceur

SystemJS Traceur Plugin
===

Provides Traceur transpilation in the browser and in builds when using SystemJS 0.19.12+ and SystemJS Builder 0.15+.

Compatible with the the automatic Rollup optimizations in SystemJS Builder.

Usage

$3

``
jspm install plugin-traceur
`

Then set transpiler: 'plugin-traceur' in the jspm.js config file.

Alternatively use jspm init -p to set up the plugin automatically.

$3

As well as this plugin, Traceur and Traceur Runtime must be manually configured.

This plugin is available at npm install systemjs-plugin-traceur.

Traceur can be installed via npm install traceur or from GitHub at https://github.com/jmcriffey/bower-traceur and https://github.com/jmcriffey/bower-traceur-runtime.

The npm version contains traceur.js and traceur-runtime.js within the bin folder.

The plugin can be used in SystemJS with the following configuration:

`javascript
SystemJS.config({
map: {
'plugin-traceur': 'path/to/systemjs-plugin-traceur/plugin-traceur.js',
'traceur': 'path/to/traceur.js',
'traceur-runtime': 'path/to/traceur-runtime.js'
},
meta: {
'traceur': {
format: 'global',
exports: 'traceur'
},
'traceur-runtime': {
format: 'global',
exports: '$traceurRuntime'
}
},
transpiler: 'plugin-traceur',
transpilerRuntime: false
});
`

_It is important to set the transpilerRuntime: false option so that Traceur doesn't interfere with the deprecated internal Traceur compilation layer of SystemJS._

The metadata above is necessary otherwise Traceur will not load property in SystemJS.

The plugin can also be configured as a loader through metadata in SystemJS.

$3

Traceur compilation options can be set via traceurOptions in SystemJS:

`javascript
SystemJS.config({
traceurOptions: {
asyncFunctions: true
}
});
`

The full list of configuration options can be found at https://github.com/google/traceur-compiler/blob/master/src/Options.js#L25.

$3

Build support works with no further configuration through the standard jspm build and bundle commands.

To build with SystemJS builder, use the following build configuration:

`javascript
builder.bundle('app.js', 'out-bundle.js'); // create a named bundle
builder.buildStatic('app.js', 'out-static.js', { format: 'cjs' }); // create a static optimized build
`

When using builder.buildStatic, the ES module structure will be preserved and Rollup optimizations will included automatically
allowing for static dead code removal.

Because Traceur runtime is a global, it can't be included in the Rollup optimizations.
It can be useful to entirely separate out the traceur-runtime dependency from the build and have it in its own bundle, for example via:

`javascript
builder.buildStatic('app.js - traceur-runtime', 'out-static.js', { format: 'cjs' });
``

This way, the entire bundle runs through Rollup for a fully-optimized output.

LICENSE
---

MIT