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Sri Sai Jyothi
Sri Sai Jyothi

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Describing For loops in JavaScript

1. The Standard For loop

let numbers = [10,20,30];
for(i = 0; i < a.length; i++ ){

πŸ‘‰ We can use break, continue, and return inside of the standard for loop.

2. forEach Loop

let numbers = [1,2,3];
  • Now, we'll get exactly as the same output as in case of the standard for-loop.

πŸ‘‰ We CANNOT use break or continue inside forEach loop.

πŸ‘‰ We can use the return keyword (forEach is anyway a function so it doesn't make any difference to use it)

3. For-in Loop

πŸ‘‰ It is used for looping over object properties.

  • What happens if we loop through an array?
// Looping through Objects
let obj = {a:10, b:20, c:30};
for(let prop in obj){
console.log(prop) //0
console.log(typeof(prop)) //string

//Looping through an array
let numbers = [10,20,30];
for(let index in numbers){
console.log(index) //0
console.log(typeof(index)) // string❗

4. For-Of Loop

πŸ‘‰ Use for-of to loop over itterables like arrays.

let numbers = [10,20,30];
for(let index of numbers){
console.log(index) //0
console.log(typeof(index)) // number❗


  1. πŸ“ The main difference between for and forEach is the use of break, continue, and return
  2. πŸ“ The main difference between for-in and for-of is the former is used to iterate over Object properties and the latter is for iterables like arrays.

Top comments (2)

mohsenalyafei profile image
Mohsen Alyafei

Thanks for the summary of the "for" loops.

vssj01 profile image
Sri Sai Jyothi

Thank you for reading :)