JavaScript While Loop

The while loop executes a block of code as long as a specified condition is true. In JavaScript, this loop evaluates the condition before each iteration and continues running as long as the condition remains true

Here’s an example that prints from 1 to 5.

let count = 1;
while (count <= 5) {
  console.log(count);
  count++;
}

1
2
3
4
5

Syntax

while (condition) { Code block to be executed}

Using While Loop to find Traverse an Array

let arr = [10, 20, 30, 40];
let i = 0;
while (i < arr.length) {
  console.log(arr[i]);
  i++;
}

10
20
30
40

Do-While loop

A Do-While loop is another type of loop in JavaScript that is similar to the while loop, but with one key difference: the do-while loop guarantees that the block of code inside the loop will be executed at least once, regardless of whether the condition is initially true or false .

Syntax

do {   
        // code block to be executed 
 } while (condition);

Example : Here’s an example of a do-while loop that counts from 1 to 5.

let count = 1;
do {
  console.log(count);
  count++;
} while (count <= 5);

1
2
3
4
5

Comparison between the while and do-while loop:

The do-while loop executes the content of the loop once before checking the condition of the while loop. While the while loop will check the condition first before executing the content.