Ability to override build target

[shuding]

It seems that ES5 is always the build output target, and will override the project tsconfig value:

bunchee/src/rollup-config.ts

Line 85 in 1a4ade8

target: "ES5",

[huozhi]

@shuding This was intended to make sure all the output are compatible with es5, mostly for browser compatibility. Override it inside the bundler to let user configure less.
Very good callout, I was also wondering should we use mordern syntaxes for node.js project. What's your case here that you'd like to use other target besides ES5?

[shuding]

I think ES5 can be a good default, but shouldn't override user's intention in tsconfig. For example I want to try ESNext to drop IE support.

[huozhi]

TIL from styfle that we can use node version to specific ecmascript version with babel

node10 => es2018
node12 => es2019
node14 => es2020

I'll think of that later, maybe to provide a CLI option instead consuming from tsconfig to make the behavior consistent between js and ts inputs

[shuding]

Wow that’s interesting… but eventually I believe Bunchee needs its own config file. 😄

[huozhi]

Short term, consider esbuild as an alternative for testing?

Since IE is deprecated in 2022 soon, we might want to support es6 output

[koba04]

IE is now officially out of support, so it's time to change the target version.
vercel/swr#2095

[huozhi]

I'm waiting for a change on swc side so that I could adopt swc, then the target will easier to control