Name
Array.map() — compute new array elements from old
Availability
ECMAScript 5
Synopsis
array
.
map
(
f
)
array
.
map
(
f
,
o
)
Arguments
f
The function to invoke for each element of
array
. Its return values become elements of the returned array.o
An optional value on which
f
is invoked.
Returns
A new array with elements computed by the function
f
.
Description
map()
creates a new array
with the same length as array
, and
computes the elements of this new array by passing the elements of
array
to the function
f
. map()
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, and its return value is stored at
index i
of the newly created
array:
a
[
i
]
=
f
(
array
[
i
],
i
,
array
)
Once map()
has passed each
element of array
to
f
and has stored the results in the new
array, it returns that new array.
See Array.forEach() for further details.
Example
[
1
,
2
,
3
].
map
(
function
(
x
)
{
return
x
*
x
;
});
// => [1,4,9]
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