Declare JavaScript Variables

In computer science, data is anything that is meaningful to the computer. JavaScript provides seven different data types which are undefined, null, boolean, string, symbol, number, and object.

For example, computers distinguish between numbers, such as the number 12, and strings, such as "12", "dog", or "123 cats", which are collections of characters. Computers can perform mathematical operations on a number, but not on a string.

Variables allow computers to store and manipulate data in a dynamic fashion. They do this by using a "label" to point to the data rather than using the data itself. Any of the seven data types may be stored in a variable.

Variables are similar to the x and y variables you use in mathematics, which means they're a simple name to represent the data we want to refer to. Computer variables differ from mathematical variables in that they can store different values at different times.

We tell JavaScript to create or declare a variable by putting the keyword var in front of it, like so:

var ourName;

creates a variable called ourName. In JavaScript we end statements with semicolons.

Variable names can be made up of numbers, letters, and $ or _, but may not contain spaces or start with a number.


Use the var keyword to create a variable called myName.

Look at the ourName example if you get stuck.