issue-20211215: A JavaScript repository from toBeTheLight

When the page require output bundles from multiple entries，only hmr of the entry which is latest be required work in webpack5.

introduction

first.js is the output bundle first be required in html. second.js is the output bundle latest be required in html.

npm run entries require two output bundles from single complier. npm run compliers require two output bundles form multiple compliers.

hmr of first.js doesn't work in webpack5. All work in webpack4.

behavior

In webpack5，after changed first.js and second.js，only second.js has been replaced.

Single complier and multiple compilers are both not work, although there are some difference when fetching xx.[hash].hot-update.json.

reason

In webpack4，each file has its own context of hmr server and own context of module hot repalce. I guess, in webpack5, context will be overwritten by next file.

For example，in webpack5：

var currentUpdatedModulesList;
var waitingUpdateResolves = {};
function loadUpdateChunk(chunkId) {
	return new Promise((resolve, reject) => {
		waitingUpdateResolves[chunkId] = resolve;
		var url = __webpack_require__.p + __webpack_require__.hu(chunkId);
		var error = new Error();
		var loadingEnded = (event) => {
      // ......
		};
		__webpack_require__.l(url, loadingEnded);
	});
}

self["webpackHotUpdatewebpack5"] = (chunkId, moreModules, runtime) => {
  // ......
	if(waitingUpdateResolves[chunkId]) {
		waitingUpdateResolves[chunkId]();
		waitingUpdateResolves[chunkId] = undefined;
	}
};

After files loaded，first.js and second.js are all declared waitingUpdateResolves，but waitingUpdateResolves in self["webpackHotUpdatewebpack5"] will be the one from file second.js .

solution

When two files are from same complier, using optimization.runtimeChunk can resolve this bug. This make code using same context. But When two files from two compliers, can't use this solution.

relevant

webpack/webpack#423

result