Last Updated on June 7, 2026 by admin

JavaScript Loops

Hello Bloggers, Welcome to Decode Now.  In this blog we will discuss about JavaScript Loops. We’ll embark on a journey into the world of JavaScript loops, exploring their types, syntax, and practical applications.

– In JavaScript, loops are used to perform repeated tasks based on a condition.
A loop is a programming tool that is used to repeat a set of instructions.

– There are four types of loops in JavaScript are:-
1. for loop
2. for-in loop
3. for-of loop
4. while loop
5. do-while loop

– JavaScript Loop:- For Loop

-> A for loop is a control flow statement that allows you to repeatedly execute a block of code a specified number of times.

– The syntax of for loop is given below:
for (initialization; condition; increment)
{
code to be executed
}

– Here’s an example of a for loop that counts from 1 to 5 and prints the numbers:
-> Initialization: ‘let i = 1’ initializes a variable ‘i’ to 1.
-> Condition: ‘i <=5’ is the condition that checks if ‘i’ is less than or equal to 5.
-> Iteration: ‘i++’ increments the value of ‘i’ by 1 in each iteration.
The loop will execute as long as ‘i’ is less than or equal to 5, and it will print the numbers 1 through 5.

– JavaScript Loop:- For-in loop

-> The for-in loop iterates over the properties of an object.

– The syntax of for loop is given below:
for (variable in object) {
// Code to be executed for each property
}

– Here’s an example of using a ‘for-in’ loop to iterate over the properties of an object :
-> In this example, the ‘for-in loop iterates over the properties of the ‘person’ object, and for each property, it prints the property name and its corresponding value.

– JavaScript Loop:- For-of loop

-> The for-of loop is used for iterating over the values of iterable objects such as arrays, strings, maps, sets, and more.
-> A for-of loop operates on the values sourced from an iterable one by one in sequential order.

– The syntax of for-of loop is given below:
for (variable of iterable) {
// Code block to be executed
}

– Let’s see the example of for of loop in javascript:
const numbers = [1, 2, 3, 4, 5];

for (const number of numbers) {
console.log(number);
}

– JavaScript Loop:- While Loop

-> A while loop in JavaScript is a control flow statement that allows you to execute a block of code repeatedly as long as a specified condition evaluates to true.

– The syntax of while loop is given below:
while(condition) {
//Code block to be executed
}

– Let’s see the example of while loop in javascript:
<script>
var i=18;
while(i<=20)
{
document.write(i + “br/>”);
i++;
}
</script>

–  JavaScript Loop:- Do-While Loop

-> The do-while loop executes the code block at least once, and then it checks the condition. This means that the code block is executed once before the condition is tested.

-> The syntax of do-while loop is given below:
do {
//Code block to be executed
} while (condition);

– Let’s see the example of do-while loop in javascript:
let count=0;
do {
console.log(count);
count++;
} while (count < 5)

Note :-