Java script !! Advantages learn it!!

The merits of using JavaScript are:
• Less server interaction: You can validate user input before sending the page off to the server. This saves server traffic, which means less load on your server.
• Immediate feedback to the visitors: They don't have to wait for a page reload to see if they have forgotten to enter something.
• Increased interactivity: You can create interfaces that react when the user hovers over them with a mouse or activates them via the keyboard.
• Richer interfaces: You can use JavaScript to include such items as drag-and-drop components and sliders to give a Rich Interface to your site visitors.