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++;
}

This flowchart shows the working of the while loop in JavaScript. You can see the control flow in the while loop.

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

Syntax:

while (condition) {     
Code block to be executed 
}

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 .

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

Syntax:

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

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.