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Web Development‎ > ‎JavaScript‎ > ‎

How can i check if a textfield only contains digits?

This is fairly simple by using the parseInt JavaScript function in combination with the isNaN function: 

<html>
  <head>
    <script language="javascript"> 
		
      function validate() {
        var element = document.getElementById('myField');
        var numberValue = parseInt(element.value);
        if (isNaN(numberValue)) {
          alert('not a number');
        }
      }
    </script>
  </head>
  <body>
    <input id="myField" type="text" size="4"/>
    <input type="button" onclick="validate();" value="validate!!"/>
  </body>
</html>