Java Reference
In-Depth Information
Object Operators
JavaScript provides a number of operators to work with objects. The following table lists them.
naMe
introduced
Meaning
JavaScript 1.2
delete
delete obj
Deletes an object, one of its properties, or the element of
an array at the specified index. Also deletes variables
not
declared with the
var
keyword.
JavaScript 1.4
in
for (prop in somObj)
Returns
true
if
someObj
has the named property.
JavaScript 1.4
instanceof
someObj instanceof ObjType
Returns
true
if
someObj
is of type
ObjType
; otherwise,
returns
false
.
JavaScript 1.0
new
new ObjType()
Creates a new instance of an object with type
ObjType
.
JavaScript 1.0
this
this.property
Refers to the current object.
Miscellaneous operators
The following table lists miscellaneous operators.
naMe
introduced
Meaning
Conditional operator
JavaScript 1.0
(evalquery) ? v1 : v2
If
evalquery
is
true
, the operator returns
v1
;
otherwise it returns
v2
.
Comma operator
JavaScript 1.0
var v3 = (v1 + 2, v2 * 2)
Evaluates both operands while treating the two as
one expression. Returns the value of the second
operand. In this example,
v3
holds the resulting
value of
v2 * 2
.
JavaScript 1.1
typeof
typeof v1
Returns a string holding the type of
v1
, which is not
evaluated.
JavaScript 1.1
void
void(eva1)
Evaluates
eval1
but does not return a value.
