Esbuild: [Feature] add esbuild/register

[aelbore]

• this is same as ts-node/register
• run typescript without compilation/transpilation
• this could be useful if you are have a unit test thats written in typescript
• for reference https://github.com/TypeStrong/ts-node
• another use case is developing node app using typescript

[evanw]

I could see having something like this, although if it's non-trivial it's probably better as an independent 3rd-party package. Keep in mind that esbuild doesn't do type checking, so if you want type checking you'd still have to invoke the TypeScript compiler API. Also, I assume this is somewhat blocked on #136 unless you want to run execFileSync every time (which should be fine for smaller projects).

[evanw]

Update: there is now a transformSync() API function, so this should be pretty easy to implement. It would be interesting to see someone experiment with a 3rd-party package that does this.

[Hebilicious]

Referencing https://github.com/egoist/esbuild-register which works with esbuild but still need esm.

node -r esm -r esbuild-register file.ts works like ts-node file.ts for scripting purposes.

esbuild is incredible, the speed difference is quite noticeable.

[mhart]

I was looking at this too – there's one unfortunate downside to esbuild being a separate process which is that require needs to resolve synchronously – so each compilation ends up being a process invocation.

I looked into some potential ways around this – here are a couple of modules that could potentially enable synchronous communication with a persistent esbuild server process:

• https://github.com/MMhunter/node-sync-ipc
• https://github.com/JacobFischer/netlinkwrapper

I haven't looked any deeper into this, but I'd be interested to see if it could be achieved without the overhead of a process invocation each time

[evanw]

The sync IPC approach is interesting. FYI someone has tried a different approach here in case you want to look at that too: #248.

I also wanted to say that this isn't what esbuild was designed to do, so I think it's ok that esbuild is not a perfect fit for this particular problem.

[mhart]

Yeah, I wasn't trying to suggest it was esbuild's responsibility in any way – kinda surprised after all this time that Node.js doesn't have better sync primitives for communicating with processes. If spawnSync/execSync are fine, then why not?

[mhart]

I've just released ts-eager – which has a require hook (as well as a binary wrapper).

It's a little similar to esbuild-register, but it does eager compilation up-front of all files specified in your tsconfig.json (or specified tsconfig file). This works a lot faster for large projects compared with synchronous on-demand-compilation.

It also falls back to ts-node for emitDecoratorMetadata support, as this is unsupported by esbuild