```js let foo = false function bar(val) { foo = val } if (foo) { bar(true) } console.log(foo) ``` This can be compress to ```js let foo = false console.log(foo) ``` ([Rollup REPL](https://rollupjs.org/repl/?version=4.52.0&shareable=eyJleGFtcGxlIjpudWxsLCJtb2R1bGVzIjpbeyJjb2RlIjoibGV0IGZvbyA9IGZhbHNlXG5mdW5jdGlvbiBiYXIodmFsKSB7XG4gIGZvbyA9IHZhbFxufVxuaWYgKGZvbykge1xuICBiYXIodHJ1ZSlcbn1cbmNvbnNvbGUubG9nKGZvbykiLCJpc0VudHJ5Ijp0cnVlLCJuYW1lIjoibWFpbi5qcyJ9XSwib3B0aW9ucyI6e319), [Oxc playground](https://playground.oxc.rs/#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)) This requires tracking the value for each blocks.
This can be compress to
(Rollup REPL, Oxc playground)
This requires tracking the value for each blocks.