98 lines
3.0 KiB
Markdown
98 lines
3.0 KiB
Markdown
# rollup-plugin-off-main-thread
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Use Rollup with workers and ES6 modules _today_.
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```
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$ npm install --save @surma/rollup-plugin-off-main-thread
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```
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Workers are JavaScript’s version of threads. [Workers are important to use][when workers] as the main thread is already overloaded, especially on slower or older devices.
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This plugin takes care of shimming module support in workers and allows you to use `new Worker()`.
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OMT is the result of merging loadz0r and workz0r.
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## Usage
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I set up [a gist] to show a full setup with OMT.
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### Config
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```js
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// rollup.config.js
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import OMT from "@surma/rollup-plugin-off-main-thread";
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export default {
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input: ["src/main.js"],
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output: {
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dir: "dist",
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// You _must_ use either “amd” or “esm” as your format.
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// But note that only very few browsers have native support for
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// modules in workers.
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format: "amd"
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},
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plugins: [OMT()]
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};
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```
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### Auto bundling
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In your project's code use a module-relative path via `new URL` to include a Worker:
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```js
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const worker = new Worker(new URL("worker.js", import.meta.url), {
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type: "module"
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});
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```
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This will just work.
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If required, the plugin also supports plain literal paths:
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```js
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const worker = new Worker("./worker.js", { type: "module" });
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```
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However, those are less portable: in Rollup they would result in module-relative
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path, but if used directly in the browser, they'll be relative to the document
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URL instead.
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Hence, they're deprecated and `new URL` pattern is encouraged instead for portability.
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### Importing workers as URLs
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If your worker constructor doesn't match `workerRegexp` (see options below), you might find it easier to import the worker as a URL. In your project's code:
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```js
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import workerURL from "omt:./worker.js";
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import paintWorkletURL from "omt:./paint-worklet.js";
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const worker = new Worker(workerURL, { name: "main-worker" });
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CSS.paintWorklet.addModule(paintWorkletURL);
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```
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`./worker.js` and `./paint-worklet.js` will be added to the output as chunks.
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## Options
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```js
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{
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// ...
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plugins: [OMT(options)];
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}
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```
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- `loader`: A string containing the EJS template for the amd loader. If `undefined`, OMT will use `loader.ejs`.
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- `useEval`: Use `fetch()` + `eval()` to load dependencies instead of `<script>` tags and `importScripts()`. _This is not CSP compliant, but is required if you want to use dynamic imports in ServiceWorker_.
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- `workerRegexp`: A RegExp to find `new Workers()` calls. The second capture group _must_ capture the provided file name without the quotes.
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- `amdFunctionName`: Function name to use instead of AMD’s `define`.
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- `prependLoader`: A function that determines whether the loader code should be prepended to a certain chunk. Should return true if the load is suppsoed to be prepended.
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- `urlLoaderScheme`: Scheme to use when importing workers as URLs. If `undefined`, OMT will use `"omt"`.
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[when workers]: https://dassur.ma/things/when-workers
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[a gist]: https://gist.github.com/surma/a02db7b53eb3e7870bf539b906ff6ff6
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---
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License Apache-2.0
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