This chapter documents many of the JavaScript language operators, expressions and keywords.
For an alphabetical listing see the sidebar on the left.
Basic keywords and general expressions in JavaScript.
function
function
keyword defines a function expression.[]
{}
/ab+c/i
( )
Left values are the destination of an assignment.
Property accessors
object.property
and object["property"]
).new
new
operator creates an instance of a constructor.Postfix/prefix increment and postfix/prefix decrement operators.
A++
A--
++A
--A
A unary operation is operation with only one operand.
delete
delete
operator deletes a property from an object.void
void
operator discards an expression's return value.typeof
typeof
operator determines the type of a given object.+
-
~
!
Arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value.
+
-
/
*
%
A comparison operator compares its operands and returns a Boolean
value based on whether the comparison is true.
in
in
operator determines whether an object has a given property.instanceof
instanceof
operator determines whether an object is an instance of another object.<
>
<=
>=
The result of evaluating an equality operator is always of type Boolean
based on whether the comparison is true.
Operations to shift all bits of the operand.
<<
>>
>>>
Bitwise operators treat their operands as a set of 32 bits (zeros and ones) and return standard JavaScript numerical values.
Logical operators are typically used with boolean (logical) values, and when they are, they return a boolean value.
(condition ? ifTrue : ifFalse)
The conditional operator returns one of two values based on the logical value of the condition.
An assignment operator assigns a value to its left operand based on the value of its right operand.
=
*=
/=
%=
+=
-=
<<=
>>=
>>>=
&=
^=
|=
,
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