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worker-loader
worker loader module for webpackRequirements
This module requires a minimum of Node v6.9.0 and Webpack v4.0.0.Getting Started
To begin, you'll need to installworker-loader
:$ npm install worker-loader --save-dev
Inlined
// App.js
import Worker from 'worker-loader!./Worker.js';
Config
// webpack.config.js
{
module: {
rules: [
{
test: /\.worker\.js$/,
use: { loader: 'worker-loader' }
}
]
}
}
// App.js
import Worker from './file.worker.js';
const worker = new Worker();
worker.postMessage({ a: 1 });
worker.onmessage = function (event) {};
worker.addEventListener("message", function (event) {});
And run
webpack
via your preferred method.Options
fallback
Type: Boolean
Default: false
Require a fallback for non-worker supporting environments
// webpack.config.js
{
loader: 'worker-loader'
options: { fallback: false }
}
inline
Type: Boolean
Default: false
You can also inline the worker as a BLOB with the
inline
parameter// webpack.config.js
{
loader: 'worker-loader',
options: { inline: true }
}
Note: Inline mode will also create chunks for browsers without support for inline workers, to disable this behavior just set
fallback
parameter as
false
.// webpack.config.js
{
loader: 'worker-loader'
options: { inline: true, fallback: false }
}
name
Type: String
Default: [hash].worker.js
To set a custom name for the output script, use the
name
parameter. The name
may contain the string [hash]
, which will be replaced with a content dependent
hash for caching purposes. When using name
alone [hash]
is omitted.// webpack.config.js
{
loader: 'worker-loader',
options: { name: 'WorkerName.[hash].js' }
}
publicPath
Type:String
Default: null
Overrides the path from which worker scripts are downloaded. If not specified, the same public path used for other webpack assets is used.
// webpack.config.js
{
loader: 'worker-loader'
options: { publicPath: '/scripts/workers/' }
}
crossOrigin
Type:Boolean
Default: false
This is useful if you want to host your javascript and worker code on a CDN and only makes sense if you have configured a publicPath globally in webpack or local to this loader that is on a different domain than your html is served.
// **webpack.config.js**
{
loader: 'worker-loader'
options: {
publicPath: 'https://cdn.mysite.fast/',
crossOrigin: true,
}
}
Examples
The worker file can import dependencies just like any other file:// Worker.js
const _ = require('lodash')
const obj = { foo: 'foo' }
_.has(obj, 'foo')
// Post data to parent thread
self.postMessage({ foo: 'foo' })
// Respond to message from parent thread
self.addEventListener('message', (event) => console.log(event))
Integrating with ES2015 Modules
Note: You can even use ES2015 Modules if you have thebabel-loader
configured.// Worker.js
import _ from 'lodash'
const obj = { foo: 'foo' }
_.has(obj, 'foo')
// Post data to parent thread
self.postMessage({ foo: 'foo' })
// Respond to message from parent thread
self.addEventListener('message', (event) => console.log(event))
Integrating with TypeScript
To integrate with TypeScript, you will need to define a custom module for the exports of your worker// typings/custom.d.ts
declare module "worker-loader!*" {
class WebpackWorker extends Worker {
constructor();
}
export default WebpackWorker;
}
// Worker.ts
const ctx: Worker = self as any;
// Post data to parent thread
ctx.postMessage({ foo: "foo" });
// Respond to message from parent thread
ctx.addEventListener("message", (event) => console.log(event));
// App.ts
import Worker from "worker-loader!./Worker";
const worker = new Worker();
worker.postMessage({ a: 1 });
worker.onmessage = (event) => {};
worker.addEventListener("message", (event) => {});
Cross-Origin Policy
WebWorkers
are restricted by a
same-origin policy, so if
your webpack
assets are not being served from the same origin as your
application, their download may be blocked by your browser. This scenario can
commonly occur if you are hosting your assets under a CDN domain. Even downloads
from the webpack-dev-server
could be blocked. There are two workarounds:Firstly, you can inline the worker as a blob instead of downloading it as an external script via the
inline
parameter// App.js
import Worker from './file.worker.js';
// webpack.config.js
{
loader: 'worker-loader'
options: { inline: true }
}
Secondly, you may override the base download URL for your worker script via the
publicPath
option// App.js
// This will cause the worker to be downloaded from `/workers/file.worker.js`
import Worker from './file.worker.js';
// webpack.config.js
{
loader: 'worker-loader'
options: { publicPath: '/workers/' }
}