JavaScript do-while Loop

In this tutorial, you have learned what is do-while loop and how to use the do-while loop.

In this tutorial, you will learn:

Introduction JavaScript do while Loop
Syntax of the do while Loop
Flowchart of do while loop
Example 1: First JavaScript do while loop
Example 2: JavaScript do while loop with Break Statement

Introduction JavaScript `do while` Loop

The JavaScript do-while loop is also known as an exit control loop. The JavaScript do-while is test specified condition after executing a block of code. If the condition met false, at least once execute the block of code.

Syntax of the `do while` Loop

do{
   statement(s);
 } while(expression);

The do-while loop always executes the block of code least once before it check specified condition.

Because the condition is checked only after the block of code executes once. The do-while loop is called a post-test/exit control loop.

You have known above, the do while loop is known as an exit control loop. For this reason, it is possible that the block of code inside the do while loop is executed at least once, if the specified condition met false.

Flowchart of `do while` loop

do while loop flowchart

Example 1: Print 1 to 10 numbers in javascript using `do while` loop

See the following example of the do-while loop.

<script>

let count = 0;
do {
    count++;
    document.write(count + "<br>")
} while (count < 10);

</script>

How the script works:

First, define count variable and assign value to it.
Next, the do while loop checks specified condition after execute block of code, if count is less than 10 and execute the statements inside the loop body.
Next, in each do while loop iteration, increments count by 1.And After 10 iterations, the condition count < 10 met false and loop will be terminate.

The output of the script shown below:

Example 2: JavaScript `do while` loop with Break Statement

See the following example of the do-while loop.

<script>

    let count = 0;
    do {

        if(count == 5)
        break;

        count++;
        document.write(count + "<br>")
    } while (count < 10);

</script>

How the script works:

First, define count variable and assign value to it.
Next, the do while loop checks specified condition after executing block of code, if count is less than 10 and execute the statements inside the loop body.
Next, in each do while loop iteration, increments count by 1. Using a break statement, stop the execution of loop After 5 iterations.

The output of the script shown below: