Summary: Closes https://github.com/facebook/prepack/pull/1036 Differential Revision: D5950512 Pulled By: hermanventer fbshipit-source-id: 286298de30d2dbacf04657c42b5ceec17728ceda
4.4 KiB
Prepack ![Circle CI](https://circleci.com/gh/facebook/prepack.png?style=shield&circle-token=1109197a81e634fd06e162c25d309a420585acd5)
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.
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
Status
- test262 status on master branch
- code coverage report for serialization tests
- To see the status for a pull request, look for the message All checks have passed or All checks have failed. Click on Show all checks, Details, Artifacts, and then test262-status.txt or coverage-report-sourcemapped/index.html.
How to get the code
- Clone repository and make it your current directory.
git submodule init
git submodule update --init
- 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
- Get the code
yarn build
You can later runyarn watch
in the background to just compile changed files on the fly.yarn lint
yarn flow
How to run tests
- Get the code
- Make sure the code is built, either by running
yarn build
oryarn watch
yarn test
You can run individual test suites as follows:
yarn test-serializer
This tests the interpreter and serializer. All tests should pass.yarn test-test262
This tests conformance against the test262 suite. Not all will pass, increasing conformance is work in progress.
How to run the interpreter
- Get the code
- Make sure the code is built, either by running
yarn build
oryarn watch
yarn repl
This starts an interactive interpreter session.
How to run Prepack
-
Get the code
-
Make sure the code is built, either by running
yarn build
oryarn watch
. -
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
-
cat /tmp/sample.js | yarn prepack
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 gh-pages branch 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, run python -m SimpleHTTPServer
(Python 2) or python -m http.server
(Python 3) from the cloned gh-pages
branch.
At this time, a particular bundled version of Prepack is checked in to the gh-pages
branch at js/prepack.min.js
. To update the bundle, run yarn build-bundle
from the master
branch, and copy the resulting prepack.min.js
file into the gh-pages
branch into the js
directory, and submit a pull request for that change.
How to contribute
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.