javascript add an index in a foreach code example

Example 1: javascript .foreach

let colors = ['red', 'blue', 'green'];
// idx and sourceArr optional; sourceArr == colors
colors.forEach(function(color, idx, sourceArr) {
	console.log(color, idx, sourceArr)
});
// Output:
// red 0 ['red', 'blue', 'green']
// blue 1 ['red', 'blue', 'green']
// green 2 ['red', 'blue', 'green']

Example 2: foreach javascript

Used to execute the same code on every element in an array
Does not change the array
Returns undefined