What does [literal] in [array/object] mean?

Question

What does the following syntax mean:

1 in [1,2,3,5]

I know it doesn\'t search for 1 in the array. But what does it do?

I\'ve seen it u

Answer 1

It looks like a cheap way not to use a traditional for loop for each item in the array.

Your 2nd example is a for-each loop. It doesn't have the literal 1 (one).