This is more like a HTML question but has some JS involved...

I have a form to be filled out which posts the variables to a PHP script in a seperate file that retrieves info from a database and displays. Before the submit button is clicked, i need to validate the input in the text field. When a user inputs something in the text box and presses 'tab' or clicks on the next textbox, i invoke a onBlur event that goes to the appropriorate handler.

The prob is i need a form control that is invisble upto the point of validation but when i know that th input is wrong i need to make it visible. Please suggest me a way to do this.

Thank you.

I'm not 100% sure what you mean, but this may help (I'm assuming for this example that your "control" is a simple label):

<label id="control" style="display: none;">Hello World</label>

...and when you need it to be revealed:

<script>
document.getElementById("control").style.display = "block";
</script>