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Chapter 4 |  |
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Chapter 4 | |
Contents:
Expressions
Operator Overview
Arithmetic Operators
Comparison Operators
String Operators
Logical Operators
Bitwise Operators
Assignment Operators
Miscellaneous Operators
Expressions and operators are fundamental to most programming languages. This chapter explains how they work in JavaScript. If you are familiar with C, C++, or Java, you'll notice that expressions and operators in JavaScript are very similar, and you'll be able to skim this chapter quickly. If you are not a C, C++, or Java programmer, this chapter will teach you what you need to know about expressions and operators in JavaScript.
An expression is a "phrase" of JavaScript that a JavaScript interpreter can evaluate to produce a value. Simple expressions are constants (e.g., string or numeric literals) or variable names, like these:
1.7 // a numeric literal "Oh no! We're out of coffee!" // a string literal true // a Boolean literal null // the literal null value i // the variable i sum // the variable sum
The value of a constant expression is simply the constant itself. The value of a variable expression is the value that the variable refers to.
These expressions are not particularly interesting. More complex (and interesting) expressions can be created by combining simple expressions. For example, we saw that 1.7 is an expression and i is an expression, so the following is also an expression:
i + 1.7
(i + 1.7) - sum
