Web Programming with HTML5, CSS, and JavaScript

8.6 Variables

Let’s continue working our way through the code in the Hello web page’s function. Here’s the function’s first statement:

var msg;

The msg thing is a variable. You should already be familiar with variables in algebra. You can think of a variable as a box that holds a value. In this case, the msg variable will hold a string that forms a message.

Before you use a variable in JavaScript code, you should use var to declare the variable in a declaration statement. For example:

var name;
var careerGoals;

Words that are part of the JavaScript language are known as keywords. The word var is a keyword. On the other hand, name and careerGoals are not keywords because they are specific to a particular web page’s code and not to the JavaScript ...