mirror of
https://github.com/oxc-project/oxc.git
synced 2026-11-04 10:29:58 +00:00
YT
8432de6b27
If the target is `es2021` or lower, a compound assignment to a static
private field applies the operator twice, unless the left side of
`.#prop` is the class name. For example, `this.#count += k` is affected,
but `Counter.#count += k` is not.
```js
class Counter {
static #count = 10;
static add(k) {
this.#count += k;
return this.#count;
}
}
console.log(Counter.add(1)); // 11
```
The transformed code prints `21`, because it keeps `+=` and also adds
the old value on the right side:
```js
// before
_count._ += _assertClassBrand(Counter, this, _assertClassBrand(Counter, this, _count)._ + k);
// after
_count._ = _assertClassBrand(Counter, this, _assertClassBrand(Counter, this, _count)._ + k);
```
`Counter.#count += k` uses a separate branch that sets the operator to
`=`. The branch for `this.#count += k` did not set the operator. This PR
adds that line.
The new fixture `oxc/private-static-compound-assignment` covers `this`,
an object from a function call, and an object without the private field.
Its `exec.js` fails on main with `expected 21 to be 11`.
---
AI assistance was used for this change. I reviewed and tested it.