These methods are part of the “functional” aspect of JavaScript. JavaScript is a strange language in a good way. Before we get into this, know that all these methods above try to replace the “for” loop, or any other type of loop you can think of.
Some of you might be saying, “I like my loops thank you very much, it is in every language out there !”. And yes that is very true, however these make writing a whole loop for something trivial a thing of the past. So lets get on with it, its not as hard as you probably things it is.
All these methods only working on arrays. And they never modify the array you apply them to. They just return a new array.
Map
As in Mapping “X” to “Y”, or transforming X into Y. In the case of JavaScript you are making a map of your values. You basically just give it a function (could be anonymous) and it applies it to each array element, and forms a new array.
Reduce
As in reducing something to its essence, or compressing something down. In the case of JavaScript you are taking all your values in an array, and compressing them into something useful.
Filter
As in finding something based on a certain set of parameters. I think you guys kind’a already know what this particular method does.
I hope this helped you better understand Reduce, Map, and Filter 😊