JavaScript: The Definitive Guide, Fourth Edition

Operator Overview

If you are a C, C++, or Java programmer, most of the JavaScript operators should already be familiar to you. Table 5-1 summarizes the operators; you can refer to this table for reference. Note that most operators are represented by punctuation characters such as + and =. Some, however, are represented by keywords such as delete and instanceof. Keyword operators are regular operators, just like those expressed with punctuation; they are simply expressed using a more readable and less succinct syntax.

In this table, the column labeled “P” gives the operator precedence and the column labeled “A” gives the operator associativity, which can be L (left-to-right) or R (right-to-left). If you do not already understand precedence and associativity, the subsections that follow the table explain these concepts. The operators themselves are documented following that discussion.

Table 5-1. JavaScript operators

P	A	Operator	Operand type(s)	Operation performed
15	L	.	object, identifier	Property access
	L	[]	array, integer	Array index
	L	( )	function, arguments	Function call
	R	new	constructor call	Create new object
14	R	++	lvalue	Pre- or post-increment (unary)
	R	--	lvalue	Pre- or post-decrement (unary)
	R	-	number	Unary minus (negation)
	R	+	number	Unary plus (no-op)
	R	~	integer	Bitwise complement (unary)
	R	!	boolean	Logical complement (unary)
	R	delete	lvalue	Undefine a property (unary)
	R	typeof ...