Array forEach()

forEach() accepts two arguments:

a function to run on each item and
an optional scope object

forEach() runs the given function on every item in the array. forEach() has no return value.

The function passed in receives three arguments:

the array item value,
the position of the item in the array
the array object itself.

It is the same as iterating over an array with a for loop.

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">
        var numbers = [1,2,3,4,5,4,3,2,1]; 
        
        numbers.forEach(function(item, index, array){ 
            document.writeln(item);
        }); 
        //1 2 3 4 5 4 3 2 1
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

forEach() does not change the values contained in the array.