What is the difference between ( for… in ) and ( for… of ) statements in JavaScript?

Question

I know what is for... in loop (it iterates over key), but heard the first time about for... of (it iterates over value).

I am confused with

Answer 1

Another difference between the two loops, which nobody has mentioned before:

Destructuring for...in is deprecated. Use for...of instead.

Source

So if we want to use destructuring in a loop, for get both index and value of each array element, we should to use the for...of loop with the Array method entries():

for (const [idx, el] of arr.entries()) {
    console.log( idx + ': ' + el );
}