how to create controls dynamically using javascript

I will say that will be an bad idea of creating TextBox using Javascript. But still you can use document.createElement method to create the html 'input' control (TextBox). You need to set "type", "name", and must have attributes as "runat = server" to access the control in code behind. Atlast you need to save the control to form using method document.forms[0].appendChild(). Using "Request" method you need to find and retrive the TextBox values in code behind.