If you're talking about Google's homepage, the answer is "a lot". You can check for yourself - go to google.com, select "view source" and compare the amount of Closure-compiled JavaScript against HTML markup.
> Google's primary web search feature could, in theory, be implemented without a line of JavaScript
...and yet, in practice, Google defaults to a JavaScript-heavy implementation. Search is Google's raison d'être and primary revenue driver, I posit it therefore is optimized up the wazoo. I wouldn't hastily assume incompence given those priors.
Google homepage is 2MB. Two fucking megabytes. Without JS, it's 200K.
I can't be the only person who remembers when Google was known for even omitting technically optional html tags on their homepage, to make it load fast - they even documented this as a formal suggestion: https://google.github.io/styleguide/htmlcssguide.html#Option...
This was back when a large fraction of search users were on 56k modems. Advances in broadband connectivity, caching, browser rendering, resource loading scheduling, and front-end engineering practices may result in the non-intuitive scenario where the 2MB Google homepage in 2024 has the same (or better!) 99-percentile First-Meaningful-Paint time as a stripped-down 2kb homepage in 2006.
The homepage size is no longer that important because how much time do you save by shrinking a page from 2MB to 300kb on a 50mbps connection with a warm cache?Browser cache sizes are much larger than they were 10 years ago (thanks to growth in client storage). After all, page weight is mostly used as a proxy for loading time.
Either performance is so critical that a few kb to do feature detection is too much, or line performance has improved so much that 2MB of JavaScript for a text box and two buttons is "acceptable".
You can't have it both ways.
