Framework for building libraries and npm packages for Front-End

Commands

• npm login
• npm publish - to publish / update a package
• npm unpublish [package_name] - to delete

Framework structure

The framework allows you to write code in the form of Typescript and SCSS, code that will be compiled in JavaScript and CSS.

The output will be placed inside dist folder and it's represented by two files.

• my-library.js - you JS and CSS code bundled in one file
• my-library.d.ts - types for your code

The SCSS files need to be imported in the main TypeScript file.

Default, Webpack is configured to include the CSS code inside the JavaScript file which will create the <style></style> tag and populate it with the corresponding style.

If you want to place the CSS output in a separate file and have them both included in your application then cut these lines from config object

{
test: /\.s?css$/,
use: [
    'style-loader',
    {
        loader: 'postcss-loader',
        options: {
            config: {
                path: 'postcss.config.js',
            },
        },
    },
    'sass-loader',
    ],
},

and place them here

module.exports = (env, argv) => {
  if (argv.mode === 'development') {
    // * add some development rules here
  } else if (argv.mode === 'production') {
    // * add some prod rules here
  } else {
    throw new Error('Specify env');
  }

  return config;
};

Full example:

module.exports = (env, argv) => {
  if (argv.mode === 'development') {
    // * scss
    config.module.rules.push({
      test: /\.s?css$/,
      use: [
        'style-loader',
        {
          loader: 'postcss-loader',
          options: {
            sourceMap: true,
            config: {
              path: 'postcss.config.js',
            },
          },
        },
        'sass-loader',
      ],
    });
  } else if (argv.mode === 'production') {
    config.module.rules.push({
      test: /\.s?css$/,
      use: [
        'style-loader',
        {
          loader: 'postcss-loader',
          options: {
            config: {
              path: 'postcss.config.js',
            },
          },
        },

        'sass-loader',
      ],
    });
  } else {
    throw new Error('Specify env');
  }

  return config;
};

Start developing your library (and testing)

1. Inside src folder, change the name of the main file, from my-library.ts to the desired filename.
2. Update this name inside package.json in main and types properties.
3. Update this name in webpack.config.js in entry and output properties.
4. To test your code just import it in any test file like in the example from test folder.
5. To test the code on the UI, update the <script></script> tag in index.html file from demo folder.
6. Open index.html with a Live Server or as a simple file and test the library.

Browser or node

If your library it's made to be used by the browser, then set the target to web. If it's made to be used in the NodeJS environment, then set it to node.

In order for the library to be used both as a module and as a global object available in window, then use this properties:

libraryTarget: 'umd',
globalObject: 'this',
umdNamedDefine: true,

webpack.config.js

target: 'web',
entry: {
    index: './src/my-library.ts',
},
output: {
    path: path.resolve(__dirname, './dist'),
    filename: 'my-library.js',
    library: 'MyLibrary',
    libraryTarget: 'umd',
    globalObject: 'this',
    umdNamedDefine: true,
},

The exports are available under the name set in library property.

index.html

<script src="./dist/my-library.js"></script>
<script>
  const { isPrimeNumber } = window.MyLibrary;
</script>

.js or .ts file

import { isPrimeNumber } from '../src/my-library';

Default export

If you want to export by default, you can add the following property, libraryExport: 'default', in webpack.config.js under config.output.

Then, in your main library file use export default, for example export default class MyClass{}.

Publishing

• In package.json add a new property named files, with the location to your distribution code.

  "files": [
      "dist"
  ],

• Build before publish - you can add this property inside package.json in scripts object, if you need a hook before you publish your package. This command will be executed when you run npm publish, but before publishing the code.

  "prepublishOnly": "webpack --mode=production",

• Versioning - each time you run npm publish, be sure to update the version in "version": "1.0.0" property inside package.json. Otherwise you won't be able to deploy a new version.

• Ignoring files - use .npmgignore in the same way as .gitignore, but for npm

Testing

For more indeepth testing, Jest and Cypress are configured and they both contain a dummy example.

Jest

npm run test npm run test:watch npm run test:cov

Cypress

• start a live server to serve the index.html file from demo folder.
• in cypress/integration/test.spec.js update the URL if required.
• run npx cypress open

CDN

Each npm package is available on UNPKG. This fits very well if your library is made for the web.