- What is a function?
- Pre-defined functions
- Scope of Variables
- Function Expressions
- Anonymous Functions
- Callback Functions
- What is an object?
- Accessing Object Properties
- Calling an Object’s Methods
- Altering Properties/Methods
Array Properties and Methods
- The length property
- Stack Methods
- Queue Methods
- Reordering Methods
- Manipulation Methods
- Location Methods
- Iterative Methods
- Working with array of objects
- The Document Object Model
- Node Relationships
- Working with the Contents of Elements
- Getting Elements by ID, Tag Name, or Class
- Adding and removing element
Handling Input and Output
Ajax and JSON
- The push() method accepts any number of arguments and adds them to the end of the array, returning the array’s new length.
- The pop() method, on the other hand, removes the last item in the array, decrements the array’s length, and returns that item.
Consider this example:
var colors = [ ]; //create an array var count = colors.push("red", "green"); //push two items alert(count); //2 count = colors.push("black"); //push another item on alert(count); //3 var item = colors.pop(); //get the last item alert(item); //"black" alert(colors.length); //2
In this code, an array is created for use as a stack (note that there’s no special code required to make this work; push() and pop() are default methods on arrays). First, two strings are pushed onto the end of the array using push(), and the result is stored in the variable count (which gets the value of 2). Then, another value is pushed on, and the result is once again stored in count. Because there are now three items in the array, push() returns 3. When pop() is called, it returns the last item in the array, which is the string “black”. The array then has only two items left. The stack methods may be used in combination with all of the other array methods as well, as in this example:
var colors = ["red", "blue"]; colors.push("brown"); //add another item colors = "black"; //add an item alert(colors.length); //4 var item = colors.pop(); //get the last item alert(item); //"black"
Here, an array is initialized with two values. A third value is added via push(), and a fourth is added by direct assignment into position 3. When pop() is called, it returns the string “black”,
which was the last value added to the array.
Create an array of elements and then add three elements to the end of the array.
var flowers = ['Rose', 'Marigold']; flowers.push('Lily', 'Lotus', 'Sunflower');
Create an array of elements and then remove the last element of the array.
var birds = ['Peacock', 'Owl', 'Swan']; birds.pop();
Create an array of elements and then remove the last element of the array and then print the removed element in the console.
var food = ['burger', 'pizza', 'momo']; var removed = food.pop(); console.log(removed);