online code preview

This code provides a simple web interface where users can input code in a textarea, click the "Preview" button, and see the live HTML rendering in an iframe. 

In this code: The textarea is where you can write your code. The button triggers the previewCode function when clicked. The iframe is where the code will be previewed. The previewCode function gets the code from the textarea, opens the iframe for writing, writes the code into it, and then closes it. Please note that this is a very basic example and might not work with complex code.