JavaScript arrays loops.

Question

Hi guys. I tried to loop on an array and I don't understand why the results are different. The array is : var names =["Joe", "Don", "Theo", "Drew"]. When I use : for(var i in names) {console.log(i)}, I get 1,2,3,4. But when I use for(var i of names) {console.log(i)}, I get Joe, Don, Theo, Drew. Can someone please explain to me why?

Answer 1

"in" is used to iterate over an object. So in

for (var i in names)

names[i] can be used to get the values (i iterates over the keys). When "in" is used to iterate over an array, i takes the value of the index.

With

for (var i of names)

i takes the value of each element. "in" is not recommended to be used to iterate over an array.

More info: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in
and

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of

Answer 2

Thanks for the reply, very helpful