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运算符(Operator )

2013年10月07日 ⁄ 综合 ⁄ 共 1591字 ⁄ 字号 评论关闭

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

any

Return data type (unary)

 

R

void

any

Return undefined value (unary)

13

L

*, /, %

numbers

Multiplication, division, remainder

12

L

+, -

numbers

Addition, subtraction

 

L

+

strings

String concatenation

11

L

<<

integers

Left shift

 

L

>>

integers

Right shift with sign-extension

 

L

>>>

integers

Right shift with zero extension

10

L

<, <=

numbers or strings

Less than, less than or equal

 

L

>, >=

numbers or strings

Greater than, greater than or equal

 

L

instanceof

object, constructor

Check object type

 

L

in

string, object

Check whether property exists

9

L

==

any

Test for equality

 

L

!=

any

Test for inequality

 

L

===

any

Test for identity

 

L

!==

any

Test for non-identity

8

L

&

integers

Bitwise AND

7

L

^

integers

Bitwise XOR

6

L

|

integers

Bitwise OR

5

L

&&

booleans

Logical AND

4

L

||

booleans

Logical OR

3

R

?:

boolean, any, any

Conditional operator (3 operands)

2

R

=

lvalue, any

Assignment

 

R

*=, /=, %=, +=, -=, <<=, >>=, >>>=, &=, ^=, |=

lvalue, any

Assignment with operation

1

L

,

any

Multiple evaluation

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