After many trial and errors, this seem to be the best way to remove
break stmts in switch cases,
This change targets only last break in last case of switch smts if its
unlabelled
this change differs from #23914 as its no longer targets all branches as
that should not be no longer necessary if all cases are correctly
rewritten
https://github.com/oxc-project/oxc/issues/24672
-----
cases like `switch (a) { case 3: if (b) break; }` are not changed
-----
ref: #17544
## Summary
Mark side-effect-free `new` constructions pure so they are dropped when unused (and annotated for downstream tree-shaking):
- **TypedArrays** with a non-negative numeric-literal length (`new Int8Array(8)`, `new Uint8Array(1024)`). The buffer allocation runs no user code; a valid length is pure and a too-large length only throws a maximum-length `RangeError`, which the minifier is allowed to drop (see `docs/ASSUMPTIONS.md`). `new Int8Array(-1)` (negative-length `RangeError`), `new Int8Array(0n)` (BigInt `TypeError`), object, and non-literal arguments are kept.
- **`new Set([...])` / `new Map([[..], ..])`** with array-literal arguments; element side effects are preserved when the construction is dropped. `WeakSet`/`WeakMap` are excluded (their keys must be objects, so `new WeakSet([1])` throws), and `Map` entries must be array literals (`new Map([1])` throws).
This matches esbuild's per-constructor handling — the only other minifier that keeps every throwing form; Rollup, Terser (`unsafe`), and SWC drop some of these incorrectly. Cross-verified against the ES spec, esbuild, Terser, Rollup, and SWC.
Minified-size impact: react.development.js −0.04 kB; size-neutral elsewhere (real code uses dynamic buffer lengths, not numeric literals).
Fix a mistake in our (internal) types: `walkProgramWithCfg` was missing that elements can be `CfgVisitFn`.
Also refactor the types for `walkProgram`, importing the original `VisitFn` and `EnterExit` types from where they're defined.
Pure refactor.
Remove a few remaining instances of the pattern where we destructure global objects at top level e.g. `const { isArray } = Array;`.
In Oxlint, TSDown plugin already performs this optimization. In `napi/parser`, we intend to build the package with TSDown, and we'll apply the same optimization in build process then too.
By hoisting `let enter;` up out of the the `if` block, minifier is able to convert the `if` statement into a `&&` expression, resulting in tighter minified output.
This optimization is only visible in the bundled output, as that's where we do more aggressive minification.
Pure refactor. Generate the JS files containing `NODE_TYPE_IDS_MAP` as variants of a single source code file, instead of constructing to two different versions for parser and linter manually.
This makes changes in further PRs to come easier to implement.
Armano