Idea: double-save to refresh browser

[ericclemmons]

tldr; Save a file once, everything's normal. Save a file twice (like a double-tap), browser refreshes.

Scenario

_Web app that shows how much of a product is left in stock.

1. I'm viewing a product page: 1 left in stock.
2. I add it to my cart.
3. Open a separate window, viewing that same product, I still see 1 left in stock, even though it's in Step 1's cart.
4. I realize there's a bug in my API from showing the correct total.
5. I fix the bug in the API, save the code, HMR reloads the server-code. The browser still isn't in sync, though without a refresh.
6. I save the code again, webpack doesn't build anything (no changes), but the browser HMR sends a reload event and I correctly see 0 left in stock.

---

I'm asking here because webpack-hot-middleware is what's triggering reload events in the browser and seems like a likely place to be able to trigger the event.

Cool DX, but doable? I'd be happy to help if you can help me figure out where to even do this.

[glenjamin]

Interesting idea, it's possibly doable - depending on what the granularity of the file change event is after a save.

At the moment I just let webpack watch the filesystem, so we would need to reach into webpack and grab the watchpack instance somehow - then compare timestamps of change events.

Another similar option might be to have the middleware expose an HTTP endpoint which sends a force-reload message, and then have editor plugins ping that endpoint on a custom keybinding.

[ericclemmons]

@glenjamin Makes sense to me. I've finagled with Webpack a bit, so if I can work it out would you be open to a PR?

(If it doesn't fit within this project, it can likely be a plugin instead).

[glenjamin]

I'm happy to take a PR, possibly behind an option that's off by default initially.

[ericclemmons]

@glenjamin I <3 you. I'll see what I can do :)

[ericclemmons]

@matthiasak Pinging you since this came from our discussion!

[matthiasak]

@ericclemmons @glenjamin

I don't have a ton of experience with the lower internals of webpack or webpack-hot-middleware, but I imagine you'll need to keep track of file hashes for the server-side code separately from the client-side.

In https://github.com/matthiasak/universal-js-boilerplate-v3 I have two configs generated by my webpack.config.js. I use webpack-hot-middleware (WHM) to manage the client-side - and the webpack --watch CLI command to manage the server code. Thus, If I want WHM to track changes in the server-side code, I'd need an option kinda like serverEntry to track those changes and check subsequent file hashes against the prior version.

app.use(require("webpack-hot-middleware")(compiler, {
    serverEntry: ['/path/to/server-entry-file.js']
}))

But this might have some extra overhead in-terms of watching the server files from both the WHM and webpack --watch. Perhaps WHM can take an optional pointer to another webpack instance to hook into its changes?

let serverBundler = webpack(serverConfig)

app.use(require("webpack-hot-middleware")(compiler, {serverBundler}))

[glenjamin]

WHM can't really do anything useful with a server bundle.

There would be 2 parts to an implementation of the feature suggested here:

1. Hook into webpack/watchpack events to figure out when the reload-condition is met
2. Send a message down to the connected clients to force a reload

If you also wanted to force a refresh after server-side changes then that would hopefully only need (1) to be hooked up to the server bundle, and an appropriate method called on the middleware instance.

[ericclemmons]

I figured it made the most sense to solve it in two steps:

• Double-save to force reload for client-side bundles.
• Double-save to refresh browser when server bundle is saved.

As noted, they'll require 2 different solutions.