This loader registers the script as Web Worker
npm i -D worker-loader
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) {});
Name | Type | Default | Description |
---|---|---|---|
name |
{String} |
[hash].worker.js |
Set a custom name for the output script |
inline |
{Boolean} |
false |
Inline the worker as a BLOB |
fallback |
{Boolean} |
false |
Require a fallback for non-worker supporting environments |
publicPath |
{String} |
null |
Override the path from which worker scripts are downloaded |
name
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
webpack.config.js*
{
loader: 'worker-loader',
options: { name: 'WorkerName.[hash].js' }
}
inline
You can also inline the worker as a BLOB with the inline
parameter
webpack.config.js
{
loader: 'worker-loader',
options: { inline: true }
}
ℹ️ Inline mode will also create chunks for browsers without support for inline workers, to disable this behavior just set
fallback
parameter asfalse
webpack.config.js
{
loader: 'worker-loader'
options: { inline: true, fallback: false }
}
fallback
Require a fallback for non-worker supporting environments
webpack.config.js
{
loader: 'worker-loader'
options: { fallback: false }
}
publicPath
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/' }
}
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
ℹ️ You can even use ES2015 Modules if you have the
babel-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 = 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 = require("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/' }
}
Bogdan Chadkin |
Juho Vepsäläinen | Joshua Wiens | Michael Ciniawsky | Alexander Krasnoyarov |