In this article, We will show you the difference between JavaScript While and Do While loop with example. Although Do While loop and While loop looks similar but they differ in their execution.
- In While loop, condition is tested at the beginning of the loop and if the condition is True then only statements inside the loop will be executed. So, While loop executes the code block only if the condition is True. Please refer JavaScript While loop for further reference.
- In Do While loop, condition is tested at the end of the loop so, Do While executes the statements in the code block at least once even if the condition Fails. Please refer JavaScript Do While loop for further reference.
I think you will understand it better when you see the example so, lets write the same program using While loop and Do While loop
JavaScript While Loop Example
In this program we are declaring integer and then check whether One is greater than Ten or not. If the condition is True then it will display the Output as “X is Greater Than 10”. There is one more statement outside the While loop and this statement will be executed after the while loop.
JAVASCRIPT CODE
<!DOCTYPE html>
<html>
<head>
<title> Difference between JavaScript While and Do While loop </title>
</head>
<body>
<h1> JavaScript While Loop </h1>
<script>
var x = 1;
while (x > 10)
{
document.write("<br\> <b> X Is greater Than 10 </b>");
}
document.write("<br\> <b> Statement Outside the while loop </b>");
</script>
</body>
</html>
OUTPUT
JavaScript Do While Loop Example
We are going to write the same example using do while loop
JAVASCRIPT CODE
<!DOCTYPE html>
<html>
<head>
<title> Difference between JavaScript While and Do While loop </title>
</head>
<body>
<h1> JavaScript Do While Loop </h1>
<script>
var x = 1;
do
{
document.write("<br\> <b> X Is greater Than 10 </b>");
}while (x > 10);
document.write("<br\> <b> Statement Outside the while loop </b>");
</script>
</body>
</html>
OUTPUT
Although the condition fail, statement inside the loop is executed once because the condition is tested after the execution of the statements.
Hope you understood the difference 🙂
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You never modify x, so if the first while loop is ever true, it will crash the browser.