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⚠️ Moved to wc-tools/polymer-project-builder

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Polymer Project Builder is a utility to generate a single bundled file optimized for production from a set of HTML imports using polymer build.

It is meant to be used in projects that don't match a typical Polymer project structure, for instance, where a shell is not present, or simply where the default output of the polymer build command does not fit well.

It also adds additional build options like autoprefixer, HTML and JavaScript splitting for CSP (Content Security Policy) and the ability to change the bundle file name and the destiny path.


npm i polymer-project-builder

Command line usage

Build a project (configuration file required):



Polymer Project Builder requires a configuration file called .polymerprojectrc placed in the directory where the command is executed or in a parent directory. File paths are relative to the working directory.

Differences from polymer.json specification

The configuration file follows the polymer.json specification with some differences:

  • shell is not required.
  • entrypoint can be the main entrypoint of an application (index.html) or a file that only contains HTML imports that should be bundled into a single file. For the first case, the file should contain at least one HTML import.
  • dest allows to set the destiny path. This property is not present in the original polymer.json spec and the destiny path is set to build/[build-name | default].
  • bundleFileName allows to set the name for the HTML bundled file. Defaults to entrypoint if not set.
  • build (Object) instead of builds (Array). Polymer Project Builder generates only one build.

Build options

The build property in the configuration file accepts an object with the same options for a build using polymer build plus two additional properties:

  • csp (Boolean) Set to true to separate JavaScript from HTML. The generated JavaScript file will have the same name that the bundled file with .js extension.
  • autoprefixer (Object) An object with autoprefixer options like browsers, cascade, etc.

Example configuration file

  "entrypoint": "elements.html",
  "bundleFileName": "bundled.html",
  "extraDependencies": [
  "moduleResolution": "none",
  "dest": "dist/assets",
  "build": {
    "csp": true,
    "js": {
      "minify": true,
      "compile": true
    "css": {
      "minify": false,
      "autoprefixer": {
        "browsers": [
          "chrome >= 30",
          "firefox >= 32",
          "ios >= 9",
          "last 1 edge versions"
    "html": {
      "minify": true

Programmatically usage

Import the module and create an instance with the same options used for the command line tool.
The build() method returns a resolved promise when all the build steps have finished.

const PolymerProjectBuilder = require('polymer-project-builder');

const config = {
  // your build options

const builder = new PolymerProjectBuilder(config);
  .then(() => console.log('Polymer project successfully built!'));


If you want to contribute, please read the


We use SemVer for versioning. For the versions available, see the tags on this repository.


See the list of contributors who participated in this project.


This project is licensed under the MIT License.


Custom build tool for Web Components built over Polymer Build








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