In today’s post i will explain to how to validate a form using javasrcipt. This is very easy & simple javasrcipt code to validate text box. JavaScript can be used to validate data in HTML forms before sending the data to web server.

Below function check if form text box is blank .If the text box is left blank, an alerts message is display as popup on the web pages, and  function returns false, and the form will not be submitted:

Javascript Code

HTML Code

Add below HTML code after body tag. In the below i have added a javascript function validateForm() and define the same function in above javascript code which will get the text box value and validate according to define rules.