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 numbers from 1 to 5:

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

Output:

1
2
3
4
5

Syntax

while (condition) {
    // Code block to be executed
}

Using While Loop to Traverse an Array

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

Output:

10
20
30
40

Do-While Loop

A do-while loop in JavaScript is like a while loop, but it always runs the code at least once, even if the condition is false initially. It then continues looping as long as the condition remains true.

Syntax

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

Example: Counting from 1 to 5

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

Output:

1
2
3
4
5

Comparison Between While and Do-While Loop