Feature request - Add events for prerender phases

[gregjopa]

Zoid has the following event feature for tracking when rendering completes: https://github.com/krakenjs/zoid/blob/main/docs/api/create.md#listening-to-zoid-events. These RENDER and RENDERED events work great for measuring rendering performance. However, we are missing events for knowing when the prerender phase is complete with prerenderTemplate.

To solve this problem let's add the following new events for hooking into the prerender lifecycle:

1. onPrerender (EVENT.PRERENDER) - prerender starts
2. onPrerendered (EVENT.PRERENDERED) - prerender finishes

    prerenderTemplate: function containerTemplate({ doc, event }) {

        event.on(EVENT.PRERENDERED, () => {
            performance.mark('prerender-complete');
        });
        // rest of the prerenderTemplate code...
    }

[bluepnume]

Totally possible, but remember prerender is completely synchronous, so you can just do:

    prerenderTemplate: function containerTemplate({ doc, event }) {
        log('START_PRERENDER');
        
        // do the prerender
        
        log('END_PRERENDER');
    }

That said -- this won't be that useful since:

1. Prerender start will be virtually the same time as the 'render' event time, since prerender and render are kicked off at the same time
2. Prerender end will be virtually the same time as prerender start, since it's a synchronous function (always)

[gregjopa]

2. Prerender end will be virtually the same time as prerender start, since it's a synchronous function (always)

What about the time it takes to insert the prerenderFrame into the DOM? Here's the code I'm referring to.

zoid/src/parent/parent.js

Line 817 in c10ac41

writeElementToWindow(prerenderWindow, el);

. My thought is we need EVENT.PRERENDERED to include that cost.

[bluepnume]

Aaah that's fair. Yeah it's still synchronous; but definitely wouldn't hurt to measure. No objections!

[gregjopa]

Sweet thanks for the review @bluepnume!

[jmichaelterenin]

@gregjopa Are we able to pull this version (with PRERENDER/ED)? it's not available on the Cloudflare CDN and I can't get npm to install v10.1.0, as either a version or tag. Please help if you have a moment