It doesn't work with React.lazy

[rainydayDY]

If you are reporting a bug or having an issue setting up React Hot Loader, please fill in below. For feature requests, feel free to remove this template entirely.

Description

What you are reporting: when I user React.lazy, it doesn't work

Expected behavior

What you think should happen: state can remain

Actual behavior

What actually happens: state can't remain

Environment

React Hot Loader version: 4.12.19
"devDependencies": {
"@babel/core": "^7.8.3",
"@babel/plugin-proposal-class-properties": "^7.8.3",
"@babel/plugin-proposal-decorators": "^7.8.3",
"@babel/plugin-transform-runtime": "^7.8.3",
"@babel/preset-env": "^7.8.3",
"@babel/preset-react": "^7.8.3",
"babel-loader": "^8.0.6",
"express": "^4.17.1",
"html-webpack-plugin": "^3.2.0",
"webpack": "^4.41.5",
"webpack-cli": "^3.3.10",
"webpack-dev-middleware": "^3.7.2",
"webpack-dev-server": "^3.10.3",
"webpack-hot-middleware": "^2.25.0"
},
"dependencies": {
"@babel/runtime-corejs3": "^7.8.3",
"connected-react-router": "^6.7.0",
"history": "^4.10.1",
"prop-types": "^15.7.2",
"react": "^16.12.0",
"react-dom": "^16.12.0",
"react-hot-loader": "^4.12.19",
"react-redux": "^7.1.3",
"react-router-dom": "^5.1.2",
"redux": "^4.0.5",
"redux-thunk": "^2.3.0"
}

Run these commands in the project folder and fill in their results:

1. node -v: v12.15.0
2. npm -v: 6.13.4

Then, specify:

1. Operating system: mac os
2. Browser and version: chrome

Reproducible Demo

Please take the time to create a new project that reproduces the issue.

You can copy your project that experiences the problem and start removing things until you’re left with the minimal reproducible demo. This helps contributors, and you might get to the root of your problem during that process.

Push to GitHub and paste the link here.

you can use my project and reappear it : https://github.com/rainydayDY/webpack-fe

[theKashey]

Your example is too big. I've just checked this example and it works perfectly.

However there are two "modes" RHL can handle lazy with. Please try another one.
See Out-of-bound warning

If the tail update detection is not something you want or need, you can disable this behaviour by setting setConfig({ trackTailUpdates:false }).

By disabling trackTailUpdates you will activate another mode with a bit more aggressive lazy management.

[xyy94813]

@theKashey
how to run the example ??

I run the newest example with error in browser:

Uncaught TypeError: realPolyfill is not a function
    at eval (react-hot-loader.development.js:1379)
    at Object../node_modules/react-hot-loader/dist/react-hot-loader.development.js (bundle.js:1676)
    at __webpack_require__ (bundle.js:725)
    at fn (bundle.js:102)
    at eval (index.js:19)
    at Object../node_modules/react-hot-loader/index.js (bundle.js:1700)
    at __webpack_require__ (bundle.js:725)
    at fn (bundle.js:102)
    at eval (react-lifecycles-compat.es.js:8)
    at Object.eval (react-lifecycles-compat.es.js:10)

[xyy94813]

Someone say it maybe @hot-loader/react-dom problem.
hot-loader/react-dom#8 (comment)

But, It is not work for me without using @hot-loader/react-dom.

I found a interesting thins when i debugger:

1. Change a lazy load component.
2. HotLoaderClient will receive a WS msg success.
3. And react-hot-loader will target update function; The root component forceUpdate()
4. log warn: React-Hot-Loader: some components were updated out-of-bound. Updating your app to reconcile the changes.
5. lazy load component re-render
6. Nothing change in page.

react-hot-loader/src/hot.dev.js

Lines 54 to 82 in 5e226f4

	const deepUpdate = () => {
	// force flush all updates
	runInRenderQueue(() => {
	enterHotUpdate();
	const gen = getHotGeneration();
	module.instances.forEach(inst => inst.forceUpdate());
	if (configuration.trackTailUpdates) {
	let runLimit = 0;
	const checkTailUpdates = () => {
	setTimeout(() => {
	if (getHotGeneration() !== gen) {
	// we know that some components were updated, but not tracking which ones
	// even if their updates might be incorporated automatically (like lazy)
	// we dont know which one should be tracked, and which updates are important
	logger.warn(
	'React-Hot-Loader: some components were updated out-of-bound. Updating your app to reconcile the changes.',
	);
	deepUpdate();
	} else if (++runLimit < 5) {
	checkTailUpdates();
	}
	}, 16);
	};
	checkTailUpdates();
	}
	});
	};

If i wrap lazy load component by hot, `module, everything work well.

There are some question:

• Should i wrap any component if it will lazy load?
• And, why didn't update pages after lazy component re-render.

[theKashey]

Found a problem in tailUpdate - any pure/memo component could stop this "secondary" update. So if your application is good written - you will experience this problem, but only if react-dom patch is not enabled.

I don't have a "broken" example I am able to fix, so, @xyy94813 - could you try to use this version of hot.dev.js, and check is it helping in your case or not - https://github.com/gaearon/react-hot-loader/blob/b14f49b085a6b48b8eeadeeb1a4bf25c981dc71c/src/hot.dev.js

https://github.com/gaearon/react-hot-loader/pull/1448/files#diff-eb1f44974215c23befb11f74f6a2d4d4

[xyy94813]

@theKashey

This version work well for me，even i set trackTailUpdates to false.

Is it a excepted?

[xyy94813]

@theKashey

Well... Looks like it has side effects

Each child node in the chunk will be re-mounted again.

I'm not sure what is your expectation.

[theKashey]

The changes I've made could not cause remount. They were just about a bit more deeper updates.

[xyy94813]

I am stuck in confusion...

I write a minimized implementation...

Everything work well with react-hot-loader@4.12.20...
PS: lazy-component will be re-mount too...

[xuya227939]

I have also encountered the same problem，How can I solve it, for example?