Javascript Performance: While vs For Loops

Question

The other day during a tech interview, one of the question asked was \"how can you optimize Javascript code\"?

To my own surprise, he told me that while loops were

Answer 1

2016 Answer

In JavaScript the reverse for loop is the fastest. For loops are trivially faster than while loops. Be more focused on readability.

Here is some bench marking.

The following loops where tested:

var i,
  len = 100000,
  lenRev = len - 1;

i = 0;
while (i < len) {
    1 + 1;
    i += 1;
}

i = lenRev;
while (-1 < i) {
    1 + 1;
    i -= 1;
}

for (i = 0; i < len; i += 1) {
    1 + 1;
}

for (i = lenRev; - 1 < i; i -= 1) {
    1 + 1;
}