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Comment by unlog | Hacker News Reader

What we need is somehow the ability to serve the html/js and json at the same time without having to wait for the client to get the html and then do the fetch request for that json. This will save a full round trip for loading content while keeping things simple.

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If you mean avoiding the dreaded loading spinner when loading a single page app, you can add the JSON data in some script within the HTML. This is what server-side rendering frameworks like Next.JS do. In it's simplest form, just include something like:

I think you're asking for https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/103

Mozilla has it as "worth prototyping" https://mozilla.github.io/standards-positions/#http-early-hi... and their tracker entry is https://bugzilla.mozilla.org/show_bug.cgi?id=1407355

Put the HTML/CSS inside the JS, make that whole bundle cacheable, and make your "HTML" response basically be one <script> tag starting the JS and another containing the JSON response.

Folk have been using this technique for a decade or more

An alternative is to have a minimal HTML that has basically nothing except a <script> tag that connects to a WebSocket then have all content delivered over that. I've done testing with this in the past and it definitely outperforms HTTP/1.1 but maybe not HTTP/2 or HTTP/3 (never tested against those--this was several years ago).

I even wrote a web server with bundled framework (as an academic exercise) whose whole purpose was to work like this. It was basically made for delivering any given bundles of assets over a WebSocket and had some cool features like the ability to auto-encode, auto-compress, or translate from one file type to another (say, turning a PNG into a JPEG or minifiying JS/CSS) as a simple matter of modifying the configuration.

If you're going to serve all the js all the time, put it inline.

It is not faster in case the js can be cached or serviced through a faster CDN comparing to your own server.

Is it slower?

Yes, if your website that serves the webpage is slower than those CDNs, and your website cannot be cached while those js files can be cached.

This sort of sounds like what 103 Early Hints aims to resolve

https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/103

I just generate the json when loading the page and embed it as script with a nonce. Of couse I lose the caching of the "static" page but it's worth it.

Hmm, that's an interesting idea - perhaps the browser first downloads some kind of "manifest" file, which lists the required URIs, then the browser can request them all at once?

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