Failed to minify the code from this file

Question

I am authoring a JavaScript library that I want to put on npm. I am currently using that library in another project and I have added it as a dependency using its GitHub repository:

"dependencies": {
  // ... others
  "react-web-component": "LukasBombach/react-web-component",
}

I am also using Webpack with the UglifyJsPlugin. Now when I want to build my project I get an error:

Failed to compile.

Failed to minify the code from this file:

./packages/react-scripts/node_modules/react-web-component/src/index.js line 18:0

Read more here: https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#npm-run-build-fails-to-minify

error Command failed with exit code 1.

This is a problem of my library. When I remove it from my deps (and from my code) compiling works.

I cannot figure out what the problem is, my code seems pretty straight forward:

const ReactDOM = require('react-dom');
const retargetEvents = require('./retargetEvents');
const getStyleElementsFromReactWebComponentStyleLoader = require('./getStyleElementsFromReactWebComponentStyleLoader');

module.exports = {
  create: function(app, tagName, options) {
    const proto = Object.create(HTMLElement.prototype, {
      attachedCallback: {
        value: function() {
          const shadowRoot = this.createShadowRoot();
          const mountPoint = document.createElement('div');
          getStyleElementsFromReactWebComponentStyleLoader().forEach(style =>
            shadowRoot.appendChild(style)
          );
          shadowRoot.appendChild(mountPoint);
          ReactDOM.render(app, mountPoint);
          retargetEvents(shadowRoot);
        },
      },
    });
    document.registerElement(tagName, { prototype: proto });
  },
};

Inside the retargetEvents and getStyleElementsFromReactWebComponentStyleLoader requires there are simple module.export commands. You can see their source code here and here.

I have already tried publishing my library using ES6 export / import commands.

The full source code of my library (it's just these 3 files) can be found at https://github.com/LukasBombach/react-web-component

Answer 1

I found the solution!

I had some ES6 features in my code, namely foreach the ~ operator and shorthand function syntax. The uglyfier did not accept that. I needed to replace that with ES5 code and it works well now.