Validate HTML Phone number using JavaScript

How to validate an HTML textbox for phone numbers using JavaScript.

We will be using ASCII values of numbers for performing the validation on every key press.

You may want to open the ASCII table in another tab for reference.

The following code has a sample textbox and a javascript function to validate the data being entered into the textbox.

<html>

<head>

function validatePhone(){

if (event.keyCode >= 48 && event.keyCode <= 57)

event.returnValue = true;

else

event.returnValue = false;

}

</script>

</head>

<body>

Phone Number:

</form>

</body>

</html>

Every time a key is pressed, JavaScript checks if the key is in the range of numbers 0-9 (i.e. ASCII value of 48-57)

So now the input will be accepted in the text-box only if it is a number.