iframe-worker

A tiny WebWorker polyfill for the file:// protocol

Like pseudo-worker but using an iframe instead of XMLHTTPRequest. This polyfill should be mostly spec-compliant and supports importScripts. It should pretty much be a drop-in replacement, at least for modern browsers which include a constructable EventTarget and Promise.

Installation

npm install iframe-worker

Usage

You can use the polyfill from unpkg.com (recommended):

<script src="https://unpkg.com/iframe-worker/polyfill"></script>

... or include the polyfill in your Webpack build:

import "iframe-worker/polyfill"

... or use IFrameWorker programmatically:

import { IFrameWorker } from "iframe-worker"

The polyfill will automatically mount if the document is served via file://.

Caveats

In Worker scripts, importScripts is a synchronous operation which will wait for the script to be loaded and executed. While it's not possible to implement this behavior as part of an iframe, the importScripts function that is provided as part of this polyfill returns a Promise which can be awaited on. Since awaiting a non-Promise is a no-op, using await on importScripts will work in polyfilled and non-polyfilled environments.

Motivation

The main reason this polyfill exists is that some users of Material for MkDocs need to distribute their documentation as static HTML files and bundle it with their product. Users would browser the documentation locally, using the file:// protocol, which broke the search functionality of the documentation, as search is implemented as part of a web worker. This polyfill in combination with the localsearch plugin allows to use search on the file:// protocol.

License

MIT License

Copyright (c) 2020 Martin Donath

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.