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The for...in Loop - Loops | JavaScript | Repovive

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JavaScript22 sections · 783 units18h total

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The for...in Loop

Iterating keys

The for...in loop iterates over object keys:

let person = { name: "Alice", age: 30 }

for (let key in person) {
  console.log(key, person[key])
}
// Prints: name Alice, age 30

Don't use for...in on arrays. It iterates indices as strings and may include inherited properties. Use for...of for arrays instead.