Maybe a problem of webpack-5's libraryTarget:'window'

Bug report

libraryTarget:‘window’ works differently in webpack-4 and webpack-5.

What is the current behavior? I’m using the single-spa to create my apps. When I load the micro-frontend app, I did not use SystemJS, but create a script element to load javascript code and save the app object in a window object’s property. like this:

export const runScript = async (url: string) => {
  return new Promise((resolve, reject) => {
    const script = document.createElement('script');
    script.src = url;
    script.onload = resolve;
    script.onerror = reject;

    const firstScript = document.getElementsByTagName('script')[0];
    (firstScript as any).parentNode.insertBefore(script, firstScript);
  });
};

const loadApp = async (appPath: string) => {
  try {
    await runScript(`/${appPath}/index.js`);
    console.log(appPath, '=', (window as any)[appPath]);
  } catch {
    console.log("load child app's javascript file error。");
  }
  return (window as any)[appPath];
};

singleSpa.registerApplication({
  name: 'app1',
  app: () => loadApp('app1'),
  activeWhen: '/app1,
  customProps: {
  },
});

So, I use libraryTarget:‘window’ in the app1’s webpack configuration.

In webpack-4, it works. after doing this I can use window.xxx to get my app object, but when I update to webpack-5, the window.xxx becomes to a void object.

using webpack-4:

using webpack-5:

The other difference is that I use web-dev-server to start webpack-4 app, webpack serve to start webpack-5 app, is this a possible problem?

If the current behavior is a bug, please provide the steps to reproduce.

What is the expected behavior? works like webpack-4’s output code.

Other relevant information: webpack version: 5.1.3 & 4.44.2 Operating System: macos Additional tools:single-spa

[JonesClyne]

Can you fix this issue quickly, i got the same problem.

[toulondu]

Maybe you can crate simple example, I want to check it Of course, I delete some code of my original code, here is a simple example(maybe not simple enough) https://github.com/toulondu/webpack-bug-demo