JavaScript Variables

JavaScript Variables:

JavaScript Variables are containers for storing data values. Variables are declared with "var" keyword as follows.

            var x=5;
            var y=6;
            var z = x+y;

Rules for constructing names for variables are:

1) Names can contain letters, digits, underscores and dollar signs.
2) Names must be begin with a letter.
3) Names can also begin with $ and _
4) Names are case sensitive.
5) Reserved words (like javascript keywords) can not be used as names.

 JavaScript is untyped language. This means that a JavaScript variable can hold a value of any data type.

Daclaring (Creating) JavaScript Variables:
Creating a variable in JavaScript is called "declaring" a variable.

var bikeName;

After the declaration, the variable has no value. (Technically it has the value of undefined)
carName = "Hero Honda";

We can declare many variables in one statement;
var person="Pavan Kumar", bikeName="Hero Honda", price=50000;

A declaration can span multiple lines:
var person="Pavan Kumar",
bikeName="Heron Honda",
price=50000;

If we re-declare a JavaScript variable, it will not lose its value.
The variable bikeName will still have the value "Hero Honda" after the execution of these statements:
var bikeName="Hero Honda";
var bikeName;