Loops

Array.forEach()

Pass a callback function into forEach(). The first argument is the current item in the loop. The second is the current index in the array. You can name these two variables anything you want.

var sandwiches = [
	'tuna',
	'ham',
	'turkey',
	'pb&j'
];

sandwiches.forEach(function (sandwich, index) {
	console.log(index) // index
	console.log(sandwich) // value
});

// returns 0, tuna, 1, ham, 2, turkey, 3, pb&j

Works in all modern browsers, and IE9+. You can extend support back further with polyfills.