Arrays work the same way in JavaScript as they do in pretty much any other language. They are zero indexed, and you can declare a variable as an empty array or a pre-populated array. You can manipulate the items in an array, and arrays are not fixed in length:

var favFoods = ['pizza', 'cheeseburgers', 'french fries']; 
var stuff = [];        // empty array 
var moreStuff = new Array();       // empty array 
var firstFood = favFoods[0];    // => pizza

 
// array functions: 
favFoods.push('salad');    // add new item

 
// => ['pizza', 'cheeseburgers', 'french fries', 'salad'] 
favFoods.pop();        // remove the last item 
// => ['pizza', 'cheeseburgers', 'french fries'] 
var first = favFoods.shift();     // remove the first item 
// => first = 'pizza';  
// => favFoods = ['cheeseburgers', 'french fries'] 

To be more precise, you can consider arrays as extended child classes of the base Object class with extra implementations of Array functions.