npm

Does your artifact manager get in the way? Join us on Oct. 8 at 10am PT, to discuss how npm can help.Sign up »

babel-plugin-annotate-pure-calls

0.4.0 • Public • Published

babel-plugin-annotate-pure-calls

npm version Build Status npm

This plugins helps with automatic #__PURE__ annotation insertion. It add the comment to top level call expressions and new expressions in assignment contexts (those are considered by the plugin as side effect free). This helps UglifyJS to perform dead code elimination more efficiently and therefore reduces the bundle sizes for the consumers.

NOTE: It might break your code, so the caution is advised. Target audience for the plugin are libraries, which in vast major of use cases do not introduce side effects in top level calls. That doesn't mean that application bundles cannot benefit from the plugin.

Pure calls

// pure call
var inc = add(1)
 
// clearly impure - no assignment context
mutate({ prop: 'value' })

Top level calls

Top level call (in terms of this plugin) is one that gets executed during script initialization. So it is every call located at the root of a file, but also a call in an IIFE that gets executed at startup (including nested ones).

var a = topLevelCall()
 
b = function() {
  noTopLevelCall()
}
 
topLevelIIFEs = (function() {
  var c = (function() {
    var d = (function() {
      var e = topLevelCall()
    })()
  })()
})()

Installation

npm install --save-dev babel-plugin-annotate-pure-calls

Usage

Via .babelrc (Recommended)

.babelrc

{
  "plugins": ["annotate-pure-calls"]
}

Via CLI

babel --plugins annotate-pure-calls script.js

Via Node API

require('babel-core').transform('var inc = add(1)', {
  plugins: ['annotate-pure-calls'],
})

Usage with babel@6

The plugin works with babel@6, you might see unmet peer dependency warning though. If you want to get rid of it, please install @babel/core@6.0.0-bridge.1.

Similar projects

install

npm i babel-plugin-annotate-pure-calls

Downloadsweekly downloads

6,418

version

0.4.0

license

MIT

homepage

github.com

repository

Gitgithub

last publish

collaborators

  • avatar
Report a vulnerability