JavaScript for Beginners - Functions

A function is a sub program  that performs a specific task. Typically in   JavaScript you will have a script, so a file that  contains JavaScript, and it will have a lot of   different variables - something we've already talked  about - but also functions that calculate, that print,   or process data in some other way. On screen you  see a very simple function. Now before we can use   a function we have to write it or declare it,  so you know to define what it actually does.  ...