The JavaScript map() Function
The details of the `map()` Function in JavaScript
map()
is key method of an array when it comes to thinking in functional programming terms.
This example iterates a
and builds a new array with the result of executing f()
on each a
element:
const b = a.map(f)
Given an array, we can use map()
to create a new array from the initial one, and then filtering the result using filter()
. This short example creates a new array to get the first letter of each item in the list
array, and filters the one that matches A
:
const list = ['Apple', 'Orange', 'Egg']
list.map(item => item[0]).filter(item => item === 'A') //'A'
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