prepack README

The project's README from github.com/facebookarchive/prepack. As one markdown file: README.md.

Prepack Circle CI

Prepack is a partial evaluator for JavaScript. Prepack rewrites a JavaScript bundle, resulting in JavaScript code that executes more efficiently. For initialization-heavy code, Prepack works best in an environment where JavaScript parsing is effectively cached.

See the official prepack.io website for an introduction and an interactive REPL playground.

Status

We, the Prepack team at Facebook, have temporarily set down work on Prepack including the React compiler project. You won't see many Prepack PRs while we are currently prioritizing some other projects.

How to use Prepack

Install the CLI via npm,

$ npm install -g prepack

Or if you prefer yarn, make sure you get yarn first,

$ npm install -g yarn

and then install the Prepack CLI via yarn:

$ yarn global add prepack

You may need to prepend (pun intended!) the command with sudo in some cases.

Let the party begin

To compile a file and print the output to the console:

$ prepack script.js

If you want to compile a file and output to another file:

$ prepack script.js --out script-processed.js

Detailed instructions and the API can be found at Prepack CLI: Getting Started

Plugins to other tools

The following are a few plugins to other tools. They have been created and are maintained separately from Prepack itself. If you run into any issues with those plugins, please ask the plugin maintainers for support.

Test Results and Code Coverage

How to get the code

  1. Clone repository and make it your current directory.
  2. git submodule init
  3. git submodule update --init
  4. Get yarn and node, then do yarn

Note: For development work you really need yarn, as many scripts require it.

How to build, lint, type check

  1. Get the code
  2. yarn build
    You can later run yarn watch in the background to just compile changed files on the fly.
  3. yarn lint
  4. yarn flow

How to run tests

  1. Get the code
  2. Make sure the code is built, either by running yarn build or yarn watch
  3. yarn test

You can run individual test suites as follows:

How to run the interpreter

  1. Get the code
  2. Make sure the code is built, either by running yarn build or yarn watch
  3. yarn repl
    This starts an interactive interpreter session.

How to run Prepack

  1. Get the code

  2. Make sure the code is built, either by running yarn build or yarn watch.

  3. Have a JavaScript file handy that you want to prepack, for example:
    echo "function hello() { return 'hello'; } function world() { return 'world'; } s = hello() + ' ' + world();" >/tmp/sample.js

  4. cat /tmp/sample.js | yarn prepack-cli
    Try --help for more options.

How to validate changes

Instead of building, linting, type checking, testing separately, the following does everything together:
yarn validate

How to edit the website

The content for prepack.io resides in the website directory of this repository. To make changes, submit a pull request, just like for any code changes.

In order to run the website locally at localhost:8000:

  1. Build prepack into the website: yarn build && mv prepack.min.js website/js
  2. Run python -m SimpleHTTPServer (Python 2) or python -m http.server (Python 3) from the website/ directory

How to contribute

To read more about the project, check out this suggested reading wiki

For more information about contributing pull requests and issues, see our Contribution Guidelines.

License

Prepack is BSD-licensed. We also provide an additional patent grant.

prepack (facebookarchive/prepack)

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14.1K ·GitHub
Prepack
archived
What is this?Prepack is a partial evaluator for JavaScript that rewrites a JS bundle into code that executes more efficiently, especially useful for initialization-heavy code.
Is this a compiler or a runtime library?It is a CLI compiler/tool you run over a JS file to produce an optimized output file; it also has separate plugins for Rollup, Webpack, Parcel, VS Code, and Babel.
How do I run it on my code?Install the CLI via npm or yarn, then pipe a JS file through 'prepack-cli' to print optimized output to the console or write it to another file.
Is this still being developed?No, the Facebook Prepack team has temporarily halted work on the project, including the related React compiler effort, so expect few new PRs or fixes.
Can I use it on Windows and Mac, not just Linux?Yes, it's a Node.js CLI tool with no OS-specific requirements, so it runs on Windows, macOS, and Linux wherever Node 6.1+ is available.
Can I try Prepack without installing anything?Yes, the official prepack.io website has an interactive REPL playground for experimenting with the optimizer in the browser.
How reliable is Prepack's output?Conformance is checked against the test262 suite and a serializer test suite, but the README notes not all test262 cases pass yet, so correctness is still a work in progress.
Does Prepack work with my existing build pipeline?There are separately maintained plugins for Rollup, Webpack, and Parcel, plus a Visual Studio Code extension and a Babel plugin for Flow-to-Prepack model annotations.
What are similar projects?typescript-go, closure-compiler, tools, pkg, tsx, svgr, critical, vue-cli
Which topics is it in?vscode-extension, optimization, webpack, compiler, bsd, deprecated, performance, npm, tool, nodejs, library, javascript
Creator
facebookarchive
Size
18.6 MB
Stars
14.1K
Updated
CommitJan 21Releasev0.2.54Oct 08
Age
10y
Commits · 90 Days