Reconsider about using swc as JS/TS transformer

In early days, the performance of swc is much worse than esbuild (around 2 ~ 5x slower).

But recently, the author of swc landed many performance enhancements in swc project.

Now the performance of transform API is very close between @swc/core and esbuild: transform parallel benchmark results

Besides, swc have some advantages over esbuild:

• Support experimentalDecorators in TypeScript.
• Support @jsx pragma.
• Exposed transformer API, so community can customize transform plugin top on it jest-hoist-plugin.
• (Maybe) more users, deno is strongly dependent on swc (They are using swc in --no-type-check mode).

/cc @yyx990803 @kdy1

[kdy1]

As a side note, swc supports some typescript specific features like emitDecoratorMetadata which is important for some libraries and swc tries to be spec-compilant as much it can.

Also, starting from v1.2.23, which will be released within a week, swc will support @jsx pragma. (It’s already implemented, but not published yet)

[evanw]

Support @jsx pragma.

FWIW esbuild has already supported this for a long time (since July, so before the original post). @jsxFrag is also supported to control what’s used for the <>...</> syntax.