Operators

Operators

Now we will have a look at different operators you might use in JavaScript. Operators are a powerful technique to shorten and improve your script. For example you want to test if a variable x is larger than 3 and you want to see if it is smaller than 10. You might want to write it this way:

if (x>3)

if (x<10)

doanything();

The function doanything() is called if x>3 and x<10.>

if (x>3 && x<10)>

The && is called AND- operator. Then there is an OR- operator. You can use this for example if you want to check if one variable x is equal 5 or another variable y is equal 17:

if (x==5 || y==17) doanything();

The function doanything() is called when x==5 or y==17. It is also called if both comparisons are true. Comparisons are done via the == operator in JavaScript (Of course there are also <,>,<= and >=). If you know C/C++, this is the same. A single = is used to store a value in a variable. (If you know Pascal this may be a little bit confusing. Assigning a value to a variable is done in Pascal via := and comparisons with a single =)

If you want to see if a variable does not equal a certain number, this might get a little bit complicated without operators. This is done with a simple !=. So this would look like this for example: x != 17.

There are many more interesting operators which can make your programs more efficiently. Look at the documentation provided by Netscape to get a full overview of all operators you can use in JavaScript.

Last changed: 11.May'96

©1996 by Stefan Koch