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scope - Why does const work in some for-loops in JavaScript?

I do know why const doesn't work in for-loops. We need to create a new scope and copy over a value into that. So this won't fly.

for(const i = 0; i < 5; i++) console.log(i);

Whereas this will.

for(let i = 0; i < 5; i++) console.log(i);

However, I noticed that both of them work when looping though the properties of an object like this.

for(let property in thingy) console.log(property);
for(const property in thingy) console.log(property);

I'm not sure why.

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for (const property in object) works because with each iteration you get a new variable, which is scoped only to that iteration. You can easily check that by using a closure inside a loop:

for (const property in {a: 1, b: 2}) {
  setTimeout(() => {
    console.log(property);
  }, 100);
}

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