Author libraries in ES6 for Node and the browser.

Usage no npm install needed!

<script type="module">
  import to5LibraryBoilerplate from 'https://cdn.skypack.dev/6to5-library-boilerplate';



Travis build status Code Climate Test Coverage Dependency Status devDependency Status

Author libraries in ES6 for Node and the browser.


  • Author in ES6 (even the unit tests)
  • Export as ES5 & UMD
  • Mocha-Chai-Sinon testing stack
  • Unit tests that work in Node and in the browser

Getting Started

Update the metadata about the project, including the name in the LICENSE and the package.json information.

Write your code in src. The primary file is index.js (although the filename can be changed).

Run gulp build to compile the source into a distributable format.

Put your unit tests in test/unit. The gulp command runs the tests.

Gulp tasks

  • gulp - Lint the library and tests, then run the unit tests
  • gulp build - Lint then build the library
  • gulp watch - Continuously run the unit tests as you make changes to the source and test files themselves
  • gulp test-browser - Build the library for use with the browser spec runner. Changes to the source will cause the runner to automatically refresh.

Browser Tests

The browser spec runner can be opened in a browser to run your tests. For it to work, you must first run gulp test-browser. This will set up a watch task that will automatically refresh the tests when your scripts, or the tests, change.

Code Climate

This library is set up to integrate with Code Climate. If you've never used Code Climate, then you might be wondering why it's useful. There are two reasons:

  1. It consumes code coverage reports, and provides a coverage badge for the README
  2. It provides interesting stats on your library, if you're into that kinda thing

Either of these items on the list can simply be ignored if you're uninterested in them. Or you can pull Code Climate out entirely from the boilerplate and not worry about it. To do that, update the relevant Gulp tasks and the Travis build.

If you'd like to set up Code Climate for your project, follow the steps here.


This boilerplate uses JSHint and JSCS to lint your source. To change the rules, edit the .jshintrc and .jscsrc files in the root directory, respectively.

Given that your unit tests aren't your library code, it makes sense to lint them against a separate JSHint configuration. For this reason, a separate, unit-test specific .jshintrc can be found in the test directory. Unlike JSHint, the same JSCS rules are applied to both your code and your tests.


When should I consider using this boilerplate?

You're authoring a library that exports a single file, and that one file exports a single variable.

When might I not want to use this boilerplate?

You can always use this boilerplate as inspiration, but it works best for smaller libraries. If you're building a full-scale webapp, you will likely need many more changes to the build system.

What's the browser compatibility?

As a rule of thumb, this transpiler works best in IE9+. You can support IE8 by limiting yourself to a subset of ES6 features. The 6to5 caveats page does an excellent job at explaining the nitty gritty details of supporting legacy browsers.

Are there examples?

Quite a few! Check them out on the wiki.

Is there a Yeoman generator?

There sure is.


This boilerplate is, to a certain extent, easily customizable. To make changes, find what you're looking to do below and follow the instructions.

I want to change the primary source file

The primary source file for the library is src/index.js. Only the files that this file imports will be included in the final build. To change the name of this entry file:

  1. Rename the file
  2. Update the value of entryFileName in package.json under to5BoilerplateOptions

I want to change the exported file name

  1. Update main in package.json

I want to change the destination directory

  1. Update main in package.json

I want to change what variable my module exports

MyLibrary is the name of the variable exported from this boilerplate. You can change this by following these steps:

  1. Ensure that the variable you're exporting exists in your scripts
  2. Update the value of exportVarName in package.json under to5BoilerplateOptions
  3. Update the globals array in the test/.jshintrc file
  4. Check that the unit tests have been updated to reference the new value

I don't want to export a variable

  1. Ensure that your entry file does not export anything
  2. Set the property of exportVarName in package.json to be null
  3. Remove the variable name from the globals array in test/.jshintrc

My library depends on an external module

In the simplest case, you just need to install the module and use it in your scripts.

If you want to access the module itself in your unit test files, you will need to set up the test environment to support the module. To do this:

  1. Load the module in the test setup file. Attach any exported variables to global object if you'll be using them in your tests.
  2. Update both .jshintrc files to include any new global variable that you have added
  3. Add those same global variables to the mochaGlobals array in package.json under to5BoilerplateOptions