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Iterate over an array in JavaScript

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In this article, we will learn how to iterate over an array using JavaScript. There are multiple ways to do so. Arrays in JavaScript are single variables used to store different kinds of elements.

There are many ways to iterate through an array in JavaScript:

Using console.log() Method

Example: In this example, we will access simple array elements using their index number.

javascript




let array = ['geeks', '4', 'geeks'];
  
// Accessing array elements one by one
console.log(array[0]);
console.log(array[1]);
console.log(array[2]);


Output

geeks
4
geeks

There are multiple ways one can iterate over an array in JavaScript. The most useful ones are mentioned below.

Using for Loop

The for loop executes a set of instructions repeatedly until the given condition becomes false. It is similar to loops in other languages like C/C++, Java, etc.

Example: In this example we are using for loop for iteration of an array.

javascript




let array = [1, 2, 3, 4, 5, 6];
  
for (let index = 0; index < array.length; index++) {
    console.log(array[index]);
}


Output

1
2
3
4
5
6

Using while loop

A While Loop in JavaScript is a control flow statement that allows the code to be executed repeatedly based on the given boolean condition.

Example: In this example we are using while loop for iteration of an array.

javascript




let index = 0;
let array = [1, 2, 3, 4, 5, 6];
  
while (index < array.length) {
    console.log(array[index]);
    index++;
}


Output

1
2
3
4
5
6

Using forEach() Method

The forEach method calls the provided function once for every array element in the order. 

Example: In this example we are using forEach() method for iteration of an array.

javascript




let index = 0;
let array = [1, 2, 3, 4, 5, 6];
  
array.forEach(myFunction);
  
function myFunction(item, index) {
    console.log(item);
}


Output

1
2
3
4
5
6

Using every() Method

The every() method checks if all elements in an array pass a test (provided as a function). 

Example: In this example we are using every() method for iteration of an array.

javascript




let x = 0;
let array = [1, 2, 3, 4, 5, 6];
  
const under_five = x => x < 5;
  
if (array.every(under_five)) {
    console.log('All are less than 5');
}
else {
    console.log('At least one element is not less than 5');
}


Output

At least one element is not less than 5

Using map() Method

A map applies a function over every element and then returns the new array. 

Example: In this example we are using map() method for iteration of an array.

javascript




let x = 0;
let array = [1, 2, 3, 4, 5, 6];
  
let square = x => Math.pow(x, 2);
  
square = array.map(square);
  
console.log(array);
console.log(square);


Output

[ 1, 2, 3, 4, 5, 6 ]
[ 1, 4, 9, 16, 25, 36 ]

Using filter() Method

It is used to filter values from an array and return the new filtered array.

Example: In this example we are using filter() method for iteration of an array.

Javascript




let array = [1, 2, 3, 4, 5, 6];
  
let even = x => x % 2 === 0;
let evens = array.filter(even);
  
console.log(array);
console.log(evens);


Output

[ 1, 2, 3, 4, 5, 6 ]
[ 2, 4, 6 ]

Using reduce() Method

It is used to reduce the array into one single value using some functional logic.

Example: In this example we are using reduce() method for iteration of an array.

Javascript




let array = [1, 2, 3, 4, 5, 6];
  
const helperSum = (acc, curr) => acc + curr;
  
const sum = array.reduce(helperSum, 0);
  
console.log(array)
console.log(sum);


Output

[ 1, 2, 3, 4, 5, 6 ]
21

Using some() Method

It is used to check whether some array values pass a test.

Example: In this example we are usingsome() method for iteration of an array.

Javascript




let array = [1, 2, 3, 4, 5, 6];
  
const lessthanFourCheck = (element) => element < 4;
const lessthanFour = array.some(lessthanFourCheck);
  
console.log(array);
  
if (lessthanFour) {
    console.log("At least one element is less than 4")
} else {
    console.log("All elements are greater than 4 ")
}


Output

[ 1, 2, 3, 4, 5, 6 ]
At least one element is less than 4


Last Updated : 15 Mar, 2024
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