In what cases do javascript developers use the map() method?

Question

I'm learning about the map() method right now and I understand very basic examples.

var numbers = [2, 4, 6];

var double = numbers.map(function(value) {
    return value * 2;
});

My question is, in what cases do developers use the map() method to help solve problems? Are there some good resources with real world examples?

Thanks for the help!

You can use it whenever you need to create an array using the contents of another. For ex: I always use map() to create <option> elements from an array of strings. — techfoobar
– techfoobar, Commented Sep 9, 2015 at 5:20
Also check this out: colintoh.com/blog/5-array-methods-that-you-should-use-today — techfoobar
– techfoobar, Commented Sep 9, 2015 at 5:21
you can check this answer stackoverflow.com/questions/20055112/javascript-map-function — Arun AK
– Arun AK, Commented Sep 9, 2015 at 5:22
But, map is not faster way for iterate. you can see: jsperf.com/map-foreach — Sherali Turdiyev
– Sherali Turdiyev, Commented Sep 9, 2015 at 5:27

KAD · Accepted Answer · 2015-09-09 05:22:49Z

2

As @Tushar referred:

The map() method creates a new array with the results of calling a provided function on every element in this array.

So it is basically used when you need to apply certain functionality to every single element of an array and get the result back as an array with the new results.

For example doubling the numbers:

var numbers = [1, 4, 9];
var doubles = numbers.map(function(num) {
  return num * 2;
});
// doubles is now [2, 8, 18]. numbers is still [1, 4, 9]

answered Sep 9, 2015 at 5:22

KAD

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xangy · Accepted Answer · 2015-09-09 05:28:46Z

0

It basically helps to shorten your code eliminating the need of using for loop. But do remember it is used when every element of the array is manipulated because map() generates similar length of array provided.

For eg.- in the example you provided doubles will have [2, 8, 18].

where 2 correspond to 1. 4 correspond to 8. 9 correspond to 18.

answered Sep 9, 2015 at 5:28

xangy

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Gökay Gürcan · Accepted Answer · 2015-09-09 05:36:39Z

0

I recommend you to watch the whole video but your answer is at the 14th minute:

Asynchronous JavaScript at Netflix by Matthew Podwysowski at JSConf Budapest 2015

answered Sep 9, 2015 at 5:36

Gökay Gürcan

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