Name
Array.forEach() — invoke a function for each array element
Availability
ECMAScript 5
Synopsis
array
.
forEach
(
f
)
array
.
forEach
(
f
,
o
)
Arguments
f
The function to invoke for each element of
array
.o
An optional value on which
f
is invoked.
Returns
This method returns nothing.
Description
forEach()
loops through the
indexes of array
, in ascending order, and
invokes f
once for each element. For an
index i
,
f
is invoked with three arguments:
f
(
array
[
i
],
i
,
array
)
The return value, if any, of f
is
ignored. Note that forEach()
does
not have a return value. In particular, it does not return
array
.
Array Method Details
The following details apply to the forEach()
method, and also to the
related methods map()
, filter()
, every()
, and some()
.
Each of these methods expects a function as its first
argument and accepts an optional second argument. If a second
argument o
is specified, then the
function is invoked as if it was a method of
o
. That is, within the body of the
function, this
will evaluate to
o
. If the second argument is not
specified, then the function is invoked as a function (not a
method) and this
will be the
global object in non-strict code or null
in strict code.
Each of these methods notes the length of
array
before it begins looping. If the
invoked function appends new elements to
array
, those newly-added elements will
not be looped over. If the function alters existing elements that
have not yet been looped over, it is the altered values that will
be passed.
When invoked on sparse arrays, these ...
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