JavaScript 2.0-The Complete Reference, Second ... - freecodingtutorial

stack.pop(); // ["first", 10] Returns 20
stack.push(2); // ["first", 10, 2]
stack.pop(); // ["first", 10] Returns 2
stack.pop(); // ["first"] Returns 10
stack.pop(); // [] Returns "first"
Of course, you can use push() and pop() to add data to and remove data from the end of an
array without thinking of it as an actual stack.
JavaScript also provides unshift() and shift() methods. These methods work as push() and
pop() do, except that they add and remove data from the front of the array. Invoking unshift()
inserts its arguments (in order) at the beginning of the array, shifts existing elements to higher
indices, and increments the array‘s length property accordingly. For example,
var myArray = [345, 78, 2];
myArray.unshift(4,"fun");
alert(myArray);
adds two more elements to the front of the array, as shown here:
Calling shift() removes the first element from the array, returns it, shifts the remaining elements
down one index, and decrements length. You can think of shift() as shifting each element in
the array down one index, causing the first element to be ejected and returned; so, given the
previous example, if we called
myArray.shift();
we would end up with an array containing ―fun,‖ 345, 78, and 2. As with pop(), invoking shift()
on an array returns a value that can be used. For example, we could save the value shifted off
the array into a variable:
var x = myArray.shift();
You can use push() and shift() to simulate a queue. The following example illustrates the
principle. We place new data at the end of the array and retrieve data by removing the element
at index zero. The contents of the array and any return values are indicated in the comments.
var queue = [];
queue.push("first", 10); // ["first", 10]
queue.shift(); // [10] Returns "first"