History

• Javascript began with Netscape, as a scripting language to allow dynamic page elements and interaction with external (often Java) applications.
  
  

Non-programmers Welcome

• Full-featured web editing programs allow you to pick actions from a menu and have the Javascript inserted automatically.
  
  

Uses

• Javascript allows animation, movement and interaction after a web page has loaded. HTML can only display text and graphics, but Javascript reacts to a visitor's actions.
  
  

External Files

• Your web page will load faster if you store complex scripts in an external .js file (that is only called when needed) with HTML code like: script language="javascript" src="/scripts/example_script.js".
  
  

Examples

• Changing a button's color or shape when a cursor hits it, displaying different information based on the date or time of day, or producing a pop-up window with a click of a link are actions Javascript can add to a web page.
  
  

vs. Java

• Javasript and Java are both object-oriented programming languages, but Java must be compiled (like C or PASCAL) in order to run. Java creates robust, stand-alone applications, while Javascript requires a web browser to run.