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Loops in JavaScript are used to execute the
same block of code a specified number of times or while a
specified condition is true.
The while loop
The while loop is used when you want the loop to execute and
continue executing while the specified condition is true.
while (var<=endvalue)
{
code to be executed
}
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Note: The <= could be any comparing statement.
Example
Explanation: 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 10. i will increase by 1 each time
the loop runs.
<html>
<body>
<script type="text/javascript">
var i=0
while (i<=10)
{
document.write("The number is " + i)
document.write("<br />")
i=i+1
}
</script>
</body>
</html>
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Result
The number is 0
The number is 1
The number is 2
The number is 3
The number is 4
The number is 5
The number is 6
The number is 7
The number is 8
The number is 9
The number is 10
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The do...while Loop
The do...while loop is a variant of the while loop. This loop
will always execute a block of code ONCE, and then it will
repeat the loop as long as the specified condition is true. This
loop will always be executed at least once, even if the
condition is false, because the code is executed before the
condition is tested.
do
{
code to be executed
}
while (var<=endvalue)
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Example
<html>
<body>
<script type="text/javascript">
var i=0
do
{
document.write("The number is " + i)
document.write("<br />")
i=i+1
}
while (i<0)
</script>
</body>
</html>
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Result
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