Variables

JavaScript is a very forgiving language and that includes its usage of variables. Variables are a container for unknown or known values. This means that you can change the value of a variable as many times as you wish. JavaScript variables are defined only using the word var before them.

Some Quick JavaScript Rules

  • JavaScript is case sensitive, which means “myVariable” is not the same as “myvariable”.
  • JavaScript, for the most part, ignores white space. Depending on the programmer, you might see var example = “pickles”; or you might see var example=”pickles”;. I am going to try to stay consistent with the first one.

A variable in JavaScript is simply declared by:

Example
<html>
    <body>
        <script type="text/JavaScript">
            var stringExample;
            var intExample;
        </script>
    </body>
</html>

Of course, we have only declared the variables in the example above. We have not set any value to them, which means that they are currently empty or null.

Example
<html>
    <body>
        <script type="text/JavaScript">
            var stringExample ="This is a string";
            var intExample = 7;
            var booleanExample = true
        </script>
    </body>
</html>

In the example above, we can see that the variable stringExample is set to “This is a string”, where the string must be in quotes. The intExample is set to 7, since 7 is a integer, it shouldn’t be in quotes. The booleanExample is set to true, since true is a boolean value. (Quick Note: true and false are the only two values a boolean can be set to.)

Variable Naming

Try to keep a consistent naming scheme when naming variables. Notice how I divided the “words” by lowering the first word and capitalizing the letter of the next word. Also, try to name variables with a sense of what their purpose is. An example would be var numberOfTurtles = 7.

References

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