Loops execute a block of code a specified number of times, or while a specified condition is true.
The while Loop
The while loop loops through a block of code while a specified condition is true.Syntax
| while (variable<=endvalue) { code to be executed } |
Example
The example below defines a loop that starts with i=0. The loop will continue to run as long as i is less than, or equal to 5. i will increase by 1 each time the loop runs:Example
<html><body>
<script type="text/javascript">
var i=0;
while (i<=5)
{
document.write("The number is " + i);
document.write("<br />");
i++;
}
</script>
</body>
</html>
The do...while Loop
The do...while loop is a variant of the while loop. This loop will execute the block of code ONCE, and then it will repeat the loop as long as the specified condition is true.Syntax
| do { code to be executed } while (variable<=endvalue); |
Example
The example below uses a do...while loop. The do...while loop will always be executed at least once, even if the condition is false, because the statements are executed before the condition is tested:Example
<html><body>
<script type="text/javascript">
var i=0;
do
{
document.write("The number is " + i);
document.write("<br />");
i++;
}
while (i<=5);
</script>
</body>
</html>
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