Difference between revisions of "JavaScript Operators"

Revision as of 18:38, 19 April 2007

JavaScript contains a wide range of operators many of which are used frequently by the typical web designer and some that are not. The purpose of this chapter is to cover the most common operators that a web designer will need in the day to day work of building dynamic web pages.

The key operators for those looking to learn the essentials of JavaScript fall into six categories as follows:

• Assignment Operators
• Arithmetic Operators
• Comparison Operators
• String Operators
• Conditional Operators
• Boolean Operators

Assignment Operators

In Introducing JavaScript Variables we looked at the '=' assigmnent operator. This is the most basic of assigmnet operators and serves to simply assign a value to a variable. For example y = 10 assigns the value of 10 to a variable called y.

The '=' assignment operator does not make any changes to the value before it is assigned to the variable. A number of assigment operators are available, however, that perform arithmetic on the value before assigning it to the variable. These are essentially combined arithmetic and assigment operators. The most common operators of this type, and their "long hand" equivalents are shown below:

These combined operators essentially provide a short way of assigning the results of arithmetic expressesions between two variables or a variable and a value and having the result assigned to the first variable.