Variable in for loop is a string [duplicate]

Answer 1

The reason is that for .. in iterates object properties ("keys"), even for arrays. The "keys" in this case are the "indexes" of the array but it's still just object keys. As all object keys are strings, i gets a string value.

Answer 2

for (var i in [1, 2, 3]) {
    console.log(parseInt(i) + parseInt(1));
}