Use esbuild instead of rollup

[sidvishnoi]

It appears to be a lot faster!

Building respec-highlight (rollup: 2.1s, esbuild: 0.7s):

# rollup
$ time rollup -c worker/rollup.config.js
worker/respec-highlight.js → builds/...
created builds/ in 1.1s
npx rollup -c worker/rollup.config.js  0.03s user 0.15s system 8% cpu 2.154 total

# esbuild
$ time esbuild worker/respec-highlight.js --outdir=builds --bundle --minify --format=iife --global-name=hljs
builds\respec-highlight.js  37.0kb
Done in 14ms
npx esbuild worker/respec-highlight.js --outdir=builds --bundle --minify    0.09s user 0.14s system 33% cpu 0.684 total

Note: The bundle size is slightly larger (like 800 bytes).

[sidvishnoi]

Build w3c profile (with CSS, JS minification) 😱 😮

➜ time node tools/esbuild.js
node tools/esbuild.js  0.00s user 0.00s system 0% cpu 0.258 total
➜  time npm run build:w3c
npm run build:w3c  0.11s user 0.15s system 4% cpu 6.129 total

[marcoscaceres]

Do we get any other goodies from ESBuild? I guess this could be nice for the when we are running the watcher and running tests?

[sidvishnoi]

Yes. Watch mode would be a lot faster now.
We can also write ReSpec in TypeScript without waiting on slow compilation feedback, if that's something we want to pursue, for reasons..

[marcoscaceres]

One day... once we fix maybe 80% of current bugs.

[xfq]

If ReSpec is migrated to TypeScript, it may be possible to use tsc implemented in low-level languages (like Go to speed up type checking in the future.