Javascript-While loop
JavaScript includes a while loop to executes the code repeatedly till it satisfies a specified condition. The while loop only requires the condition expression.
Syntax:
while(condition expression)
{
/* code to be executed
till the specified condition is true */
}
Example:
<!DOCTYPE html>
<html>
<body>
<h1>Demo: while loop</h1>
<p id="p0"></p>
<p id="p1"></p>
<p id="p2"></p>
<p id="p3"></p>
<p id="p4"></p>
<script>
var i =0;
while(i < 5)
{
document.getElementById("p" + i).innerHTML = i;
i++;
}
</script>
</body>
</html>
OUTPUT:
Demo: while loop
0
1
2
3
4
do while:
JavaScript includes another flavor of while loop, which is a do-while loop. The do-while loop is similar to the while loop the only difference is it evaluates condition expression after the execution of the code block. So the do-while loop will execute the code block at least once.
Syntax:
do{
//code to be executed
}while(condition expression)
Example:
<!DOCTYPE html>
<html>
<body>
<h1>Demo: do while loop</h1>
<p id="p0"></p>
<p id="p1"></p>
<p id="p2"></p>
<p id="p3"></p>
<p id="p4"></p>
<script>
var i =0;
do{
document.getElementById("p" + i).innerHTML = i;
i++;
} while(i < 5)
</script>
</body>
</html>
OUTPUT:
Demo: do while loop
0
1
2
3
4
- In JavaScript, while loop and do-while loop executes the block of code repeatedly till conditional expression, returns true.
- The do-while loop executes the code at least once even if the condition returns false.