How to explain the use of in statement?

Unity Engine
1

How to explain the use of in statement?

For example, like below:

for(var b in coms) {
// code
}

2

“for (x in y)” is a for loop that iterates through the elements in y, where y is an array or other collection.

3

Thanks laurie! Seems a simple so.

4

It’s a shorter way of saying

for (var i = 0; i < coms.length; i++)
{
    var b = coms[i];
    //code
}