What's it all about
While developing a web page in fully HTML controls, you may not be able to use the
ASP.NET's controls for example if you want some validation
then you can not use the regular expression control there. So there you may need this technique for validating your HTML controls.
Using the code
Here I will show you how to validate the HTML controls using JavaScript.
Take a text input in html and a button input like this
<input type='text' id='txtEmail'/>
<input type='submit' name='submit' onclick='Javascript:checkEmail();'/>
Now when the button is clicked then the JavaScript function SubmitFunction()
will be called. Now write the bellow code in this function.
script language="javascript">
function checkEmail() {
var email = document.getElementById('txtEmail');
var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
if (!filter.test(email.value)) {
alert('Please provide a valid email address');
email.focus;
return false;
}
}</script>
Now you have successfully validate your HTML controls through JavaScript.