1.1.5 • Public • Published


    CircleCI semantic-release Commitizen friendly npm version

    This is my personal skeleton for creating an npm package with JS(/flow) source code.


    • All source files are in src
    • Test files are in test. You can override this by specifying options for mocha in ['@jcoreio/js'].mochaArgs in your package.json.
    • You want to publish the package via semantic-release
    • You're using CircleCI


    yarn add --dev @jcoreio/js
    yarn toolchain bootstrap

    If you want to more aggressively replace existing configuration, use yarn toolchain bootstrap --hard.

    The bootstrap script will modify your package.json, .gitignore, .circleci/config.yml and generate .babelrc.js, .eslintrc.js, and .prettierrc.js that are just proxies for the config in @jcoreio/js.

    Instead of running scripts from your package.json, you can run them with the yarn toolchain command (or yarn tc), for example yarn toolchain lint. Run yarn toolchain by itself to see all of the available commands.


    You can customize the config files created by the bootstrap process:

    • babel.config.js
    • commitlint.config.js
    • husky.config.js
    • lint-staged.config.js
    • nyc.config.js
    • prettier.config.js

    You can also set the following options in the @jcoreio/js property in your package.json:

    • mochaArgs: an array of additional arguments to mocha (default: ["test/**.js"], or .ts/.tsx depending on the toolchain)
    • noBabelRuntime: if true, disables @babel/plugin-transform-flow-runtime

    For example:

      "name": "foo",
      "@jcoreio/js": {
        "mochaArgs": ["test/index.js"]


    You can pass a second argument to the base babel config like this:

    /* eslint-env node */
    module.exports = function (api) {
      return require(`@jcoreio/js/babel.config.js`)(api, {
        envPresetOptions: {
          target: {node: 12},
          forceAllTransforms: false,
        babelRuntime: false,

    It accepts the following options:

    • envPresetOptions: overrides options for @babel/preset-env
    • babelRuntime: if false, won't use @babel/plugin-transform-runtime

    Package Publishing

    Files to publish are output/copied into the dist folder and then published from there. This includes a derived package.json with various development-only fields removed and automatically-generated main, module, and exports fields added.

    The toolchain will do the following for JS (similar for TS):

    • Transpile src/**.js to dist/**.js (CommonJS modules)
    • Transpile src/**.js to dist/**.mjs (ES modules)
    • Copy src/**.js to dist/**.js.flow
    • Copy src/**.js.flow to dist
    • Copy src/**.d.ts to dist
    • Copy *.md to dist
    • Copy package.json to dist with modifications:
      • main from root package.json or auto-generated value
      • module from root package.json or auto-generated value
      • exports from root package.json or auto-generated value
      • @babel/runtime will be added or removed from dependencies depending on whether any output code requires it
      • Removed keys:
        • config
        • devDependencies
        • files
        • husky
        • lint-staged
        • nyc
        • scripts.prepublishOnly
        • renovate


    npm i @jcoreio/js

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