A webpack plugin for deep scope analysis
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.vscode clean code Jun 11, 2018
packages v1.6.0 Sep 4, 2018
.gitignore feature: add plugin and example to packages May 30, 2018
.travis.yml fix: travis bootstrap May 30, 2018
README.md fix #9: missing 's' in READEME.md Dec 7, 2018
lerna.json v1.6.0 Sep 4, 2018
package.json refactor dependencies Jul 13, 2018


Webpack Deep Scope Analysis Plugin

npm version

A webpack plugin for deep scope analysis. It's a project of GSoC 2018 webpack organization.

It's a plugin to improve tree-shaking. It can make webpack eliminate the unused imports related to the unused exports. It solves the issue 6254 for webpack.

Student: @Vincent Mentor: @Tobias

Demo: https://vincentdchan.github.io/webpack-deep-scope-demo/


Install the plugin:

$ yarn add webpack-deep-scope-plugin


  • Node.js 8 +
  • webpack 4.14.0 +


Enable the plugin in webpack.config.js:

const WebpackDeepScopeAnalysisPlugin = require('webpack-deep-scope-plugin').default;

module.exports = {
  plugins: [
    new WebpackDeepScopeAnalysisPlugin(),

Notice: the plugin only works for import and export syntax module. If your code are transpiled to module.export and require syntax, the analyzer can't work correctly.

The plugin will analyze the scope and determine if the variables should be imported automatically.




Pure Annotation

As you know, it's difficult for ECMAScript to analyze the side effects. Hence, PURE annotation is introduced, which is from Uglify:

A function call is marked as "pure" if a comment annotation /*@__PURE__*/ or /*#__PURE__*/ immediately precedes the call. For example: /*@__PURE__*/foo();



  • rename package webpack-deep-scope-analysis to deep-scope-analyser, which is published as a new npm package. It's aimed to be a standalone analyser.


  • Fix #7: import * from 'xxx' syntax



  • Improve performance and code quality


  • Introduce VirtualScope to simulate module variable


  • Fix #4
  • Publish


Use lerna to build and test:

$ lerna run build
$ lerna run tslint
$ lerna run test

About Escope

Now the src/ includes a Typescript version of escope, because the plugin needs some internal changes of the escope manager. So I didn't import the escope directly.

When the plugin is nearly finished, I will make some PRs to the original escope repo.