Javascript Array Methods
Tags: javascript, webdev, beginners, tutorial
Published: 2020-05-18 04:51:48

In this tutorial, array methods are discussed.

Length property
---------------

[The `array.length` the property acts as a counter](http://thecodelearners.com/javascript-array/) as it keeps count on the number of items in an array. Let us look a below example
```javascript
var x = [5,8,7,2,1];
console.log(x.length);

//Console Output
5
```
`x.length` outputs the number of items in array x.

push() method
-------------

The method `push()` is used to insert an item into the end of the array.

#### Syntax
```javascript
array.push(item1,item2,...);
```
We can insert a single item or multiple items at once.

#### Example
```javascript
var items = ["Key", "Soap", "Table"];
items.push("Slippers", "Napkin", "Charger");
console.log(items)

//Console Output
(6) ["Key", "Soap", "Table", "Slippers", "Napkin", "Charger"]
```
pop() Method
------------

The method `pop()` remove the last item from the array and return the remove item.

#### Syntax
```javascript
array.pop()
```
#### Example
```javascript
var items = ["Key", "Soap", "Table"];
items.push("Slippers", "Napkin", "Charger");
console.log("Array before pop() method ",items)
items.pop()
console.log("Array after pop() method ",items)

//Console Output
Array before pop() method (6) ["Key", "Soap", "Table", "Slippers", "Napkin", "Charger"]
Array after pop() method (5) ["Key", "Soap", "Table", "Slippers", "Napkin"]          
```
shift() Method
--------------

The method `shift()` does the opposite of the`pop()` method. It removes the first item from an array.

#### Syntax
```javascript
array.shift()
```
#### Example
```javascript
var items = ["Key", "Soap", "Table"];
console.log("Array before shift() method ",items);
items.shift();
console.log("Array after shift() method ",items);

//Console Output
Array before shift() method  (3) ["Key", "Soap", "Table"]
Array after shift() method  (2) ["Soap", "Table"]
```
unshift Method
--------------

The method `unshift` does the opposite of the `push()` method inserts a new item at the start of the array and returns a count for a number for items in an array.

#### Syntax
```javascript
array.unshift(item1,item2,...);
```
#### Example
```javascript
var items = ["Key", "Soap", "Table"];
console.log("Array before unshift() method ",items);
items.unshift("Knife", "Medicine box", "Toilet Paper");
console.log("Array after unshift() method ",items);

//Console Output
Array before unshift() method  (3) ["Key", "Soap", "Table"]
Array after unshift() method  (6) ["Knife", "Medicine box", "Toilet Paper", "Key", "Soap", "Table"]
```
indexOf Method
--------------

Method `indexOf` used to check if the item exists in an array. It takes two arguments first is an item to search and the second argument specifies from which index it should start searching. If search item exists in the array it returns its index and if search item doesn't exist then it will return -1 which means that the item does not exist in an array.

#### Syntax
```javascript
array.indexOf(search_item, search_from_index);
```
Argrument `search_from_index` is optional argrument.

#### Example 1
```javascript
var items = ["Key", "Soap", "Table"];
items.indexOf("Soap");

//Console Output
1 //this is index of item "Soap"
```
#### Example 2

Let us check if student name exists in array using `if-statement`.
```javascript
var students = ["Kishor", "Suresh", "Naresh", "Sunil", "Pradeep"];
var index = students.indexOf("Naresh");
if(index != -1){
    console.log("Student name 'Naresh' exists in array at index : "+index);
}else{
    console.log("Student name 'Naresh' does not exists in array");
}

//Console Output
Student name 'Naresh' exists in array at index : 2
```
slice Method
------------

The method `slice` is used to cut a particular position of an array. This method takes two arguments `start` and `end`. The `start` the argument specifies from which index it should start slicing and `end` argument specifies at which index it must stop slicing. It does not override the existing array and returns a new sliced array.

#### Syntax
```javascript
array.slice(start_index, end_index);
```
#### Example
```javascript
var students = ["Kishor", "Suresh", "Naresh", "Sunil", "Pradeep"];
var start_index = 2, end_index = 4;
students.slice(start_index, end_index);

//Console Output
(2) ["Naresh", "Sunil"]
```
[MDN Doc](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array) provides an in-detail look at javascript array methods. This post is taken from [thecodelearners website](http://thecodelearners.com/javascript-array-methods-push-pop-shift-unshift-indexof-etc/)