I am new to HTML, JS but have an extensive background using Flash (sorry for my luck, right? ;-)
Anyway, I am accustomed to developing "symbols" (Flash terminology for custom movie clips) which are then added to the project library and instantiated within a main movie. I am wondering if there is a similar concept in the HTML/JS world and what it might be termed?

For instance, I may want to have several boxes on a page, each with text, radio buttons, combo boxes, etc. but I do not want to have to retype all the code and JS. I want to create a stand alone "component" (maybe that is not the right term) that I can instantiate every time I need the custom "box" I have created. A library would contain the custom box and I would only need change in one place to affect all instantiations.

Does that make sense? If so, what is the terminology?