setTimeout in a for loop

Do you know what happens in JavaScript, if you put a setTimeout into a for loop?

or (var i = 0; i < 3; i++) {
    setTimeout(() => console.log(i), 0);
}

It will output 3, three times in a row. This is because setTimeout is a browser API that is deferred to the end of the call stack. By the time the callback function is returned to the call stack, the value of i will already be 3. To get the desired behavior, you could use a let instead:

for (let i = 0; i < 3; i++) {
    setTimeout(() => console.log(i), 0);
}

50 JavaScript Interview QuestionsAnd their answers explainedHere are 50 JavaScript interview questions that often come up during a technical interview. In one place, one resource to learn from.Learn More

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Resources:

• The setTimeout method in JavaScript