Array
An array is a single variable, which holds more than one value. A pair of square brackets [ ] can be used to symbolize an array in JavaScript.
Syntax
const array_name = [Item1,Item2,Item3,....];
Example
const fruit = ['apple','mango','grapes','orange'];
console.log(fruit);
Output
['apple','mango','grapes','orange']
Alternate Way to create an Array
const array_name = new Array("item1","item2","item3");
Example
const fruit = new Array("apple","mango","orange","grapes");
console.log(fruit);
Output
["apple","mango","orange","grapes"]
Access the elements of an array
We can access the elements of an Array using an index number.
Indexing of elements begins from 0 in arrays means the first element index is zero.
Example
const fruit = new Array("apple","mango","orange","grapes");
console.log(fruit[0]);
console.log(fruit[1]);
console.log(fruit[2]);
Output
apple
mango
orange
Array Methods
1.push()
The push() method is used to add a new element to the array (at the end).
Example
const fruit = new Array("apple","mango","orange","grapes");
fruit.push("pineapple");
console.log(fruit);
['apple','mango','orange','grapes','pineapple']
2.pop()
The pop() method is used to remove the last element of an array.
Example
const fruit = new Array("apple","mango","orange","grapes");
fruit.pop();
console.log(fruit);
['apple','mango','orange']
3.slice()
The slice() method is used to select a part of an array and returns the new array. The method has two parameters:- start and end. It selects from a given start, up to a (not inclusive) given end.
Syntax
array.slice(start,end)
Example
const fruit = new Array("apple","mango","orange","grapes");
fruit.slice(1,3);
console.log(fruit);
["mango","orange"]
4.splice()
The splice() method is used to add or remove elements from the array. It overwrites the original array.
Syntax
array.splice(index, number, item1...itemx)
index specifies the position to add/remove elements.
number specifies the number of elements to be removed.
item1..itemx specifies the items to be added.
Example
const fruit = new Array("apple","mango","orange","grapes");
fruit.splice(1,1,"pineapple");
console.log(fruit);
["apple","pineapple","orange","grapes"]
5.concat()
The concat() method is used to join two or more arrays. It returns the new array containing the joined arrays. This method does not changes the existing arrays.
Example
const array1 = ["abc","xyz"]
const array2 = ["ghi","klm"]
const array3 = array1.concat(array2);
["abc","xyz","ghi","klm"]
6.fill()
The fill() method is used to fill the specified elements in an array with a value. It overwrites the original array.
Syntax
array.fill(value,start,end)
the value specifies the value to fill in.
start specifies the starting index.
end specifies the ending index.
Example
const fruit = new Array("apple","mango","orange","grapes");
fruit.fill("pineapple",2,4)
console.log(fruit)
["apple","mango","pineapple","pineapple"]
7.includes()
The includes() method returns true if an array contains a specified value. It returns false if the value is not found. This method is case-sensitive.
Syntax
array.includes(value,start)
value specifies the value to be looked for.
start specifies the starting index to look for the value.
Example
const fruit = new Array("apple","mango","orange","grapes");
console.log(fruit.includes("mango",2))
false
8.indexOf()
The indexOf() method returns the first index (position) of a specified value. It returns -1 if the value is not found. This method starts at a specified index and searches from left to right.
Syntax
array.indexOf(value,start)
value specifies the item to be searched.
start specifies the starting index.
Example
const fruits = ["Banana", "Orange", "Apple", "Mango", "Apple"];
console.log(fruits.indexOf("Apple", 3));
4
9.isArray()
The isArray() method returns true if an object is an array, otherwise false.
Syntax
Array.isArray(obj)
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
console.log(Array.isArray(fruits));
true
10.join()
The join() method returns an array as a string. This method does not change the original array. We can use any separator but the default is a comma(,).
Syntax
array.join(separator)
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
console.log(fruits.join(" and "));
Banana and Orange and Apple and Mango
11.map()
The map() creates a new array by calling a function for every array element. It calls a function once for each element in an array. It does not changes the original array.
Example
let maths=[1,4,9,16,25]
console.log(maths.map(Math.sqrt));
[1,2,3,4,5]
12.reverse()
The reverse() method reverses the order of the elements in an array. This method overwrites the original array.
Syntax
array.reverse()
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
console.log(fruits.reverse());
["Mango","Apple","Orange","Banana"]
13.shift()
The shift() method removes the first item of an array. This method changes the original array. It returns the shifted element.
Syntax
array.shift()
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
console.log(fruits.shift());
Banana
14.sort()
The sort() method sorts the elements of an array. It overwrites the original array. This method sorts the elements as strings in alphabetical and ascending order.
Syntax
array.sort()
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
console.log(fruits.sort());
["Apple","Banana","Mango","Orange"]
15.unshift()
The unshift() method adds new elements to the beginning of an array. This method overwrites the original array.
Example
const fruits = ["Banana", "Orange", "Apple", "Mango"];
console.log(fruits.unshift("Lemon", "Pineapple"));
["Lemon","Pineapple","Banana","Orange","Apple","Mango"]
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