How to force a user to only enter numbers into a text field using JavaScript

Written by Ian Carnaghan · 20 sec read >

Add the following JavaScript function to your HTML page

	function isNumberKey(evt)
	     var charCode = (evt.which) ? evt.which : event.keyCode
	     if (charCode > 31 && (charCode < 48 || charCode > 57))
	        return false;
	     return true;

The above function checks the input of the user and then returns false if no number has been entered and true if a number has been entered

Then in your textfield HTML code add the following

onkeypress="return isNumberKey(event)"

This will check for a number on every key press from the user

<input type="text" onkeypress="return isNumberKey(event)"  name="number" />

Last Updated On March 20, 2018
Written by Ian Carnaghan
I am a software developer and online educator who likes to keep up with all the latest in technology. I also manage cloud infrastructure, continuous monitoring, DevOps processes, security, and continuous integration and deployment. Profile

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