How to validate a phone number in JavaScript

You can easily validate a TextBox against a phone number format, in JavaScript, using Regular Expressions (RegEx):

<script type=“text/javascript”>
function FormValidate()
{ if(\d{3}\-\d{3}\-\d{4}/)==-1)
alert(“The phone number you entered is not valid.\r\nPlease enter a phone number
with the format xxx-xxx-xxxx.”);
return false;

And the HTML markup that works with this script, is:

<form name=“Form1” onsubmit=“return FormValidate()”>
<input type=“text” size=“25” name=“PhoneNumber” />
<br /><br />
<input type=“submit” value=“Submit” />

See this code in action

The RegEx can be modified so that you can validate any other phone number format. For example, to validate a phone number with the format xxx-xxxx, simply use the RegEx string /\d{3}-\d{4}/.

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