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}/.

Nathan Pakovskie is an esteemed senior developer and educator in the tech community, best known for his contributions to With a passion for coding and a knack for simplifying complex tech concepts, Nathan has authored several popular tutorials on C# programming, ranging from basic operations to advanced coding techniques. His articles, often characterized by clarity and precision, serve as invaluable resources for both novice and experienced programmers. Beyond his technical expertise, Nathan is an advocate for continuous learning and enjoys exploring emerging technologies in AI and software development. When he’s not coding or writing, Nathan engages in mentoring upcoming developers, emphasizing the importance of both technical skills and creative problem-solving in the ever-evolving world of technology. Specialties: C# Programming, Technical Writing, Software Development, AI Technologies, Educational Outreach

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