Learning PHP, MySQL, and JavaScript

Operators

JavaScript offers a lot of powerful operators that range from arithmetic, string, and logical operators to assignment, comparison, and more (see Table 15-1).

Table 15-1. JavaScript operator types

Operator	Description	Example
Arithmetic	Basic mathematics	a + b
Array	Array manipulation	a + b
Assignment	Assign values	a = b + 23
Bitwise	Manipulate bits within bytes	12 ^ 9
Comparison	Compare two values	a < b
Increment/Decrement	Add or subtract one	a++
Logical	Boolean	a && b
String	Concatenation	a + 'string'

Each operator takes a different number of operands:

• Unary operators, such as incrementing (a++) or negation (-a) take a single operand.

• Binary operators, which represent the bulk of JavaScript operators, including addition, subtraction, multiplication, and division.

• One ternary operator, which takes the form ? x : y. It’s a terse single-line if statement that chooses between two expressions depending on a third one.

Operator Precedence

As with PHP, JavaScript utilizes operator precedence, in which some operators in an expression are considered more important than others and are therefore evaluated first. Table 15-2 lists JavaScript’s operators and their precedences.

Table 15-2. The precedence of JavaScript operators (high to low)

Operator(s)	Type(s)
() [] .	Parentheses, call, and member
++ --	Increment/decrement
+ - ~ !	Unary, bitwise, and logical
* / %	Arithmetic
+ -	Arithmetic and string
<< >> >>>	Bitwise
&	Bitwise
|	Bitwise
^	Bitwise
< > <= >=	Comparison
== != === !==	Comparison
&&	Logical
||	Logical
? :	Ternary
= += -= *= /= %= <<= ...