What is the function of map

Question

Map

Answer 1

In many programming languages, map is the name of a higher-order function that applies a given function to each element of a list, returning a list of results in the same order. It is often called apply-to-all when considered in functional form.

Answer 2

In normal arrays, you use an int to access your elements, right?
In a map, that mustn't be an int.

Answer 3

Hi Diwash

Map can be used to iterate through an array or object without using loops. As Brains says this is very common in Functional Programming.

Here is an JavaScript example:

// an array of objects called animals //
var animals = [{
name: "Bailey",
size: "small"
}, {
name: "Max",
size: "medium"
}, {
name: "Charlie",
size: "large"
}, {
name: "Buddy",
size: "small"
}, ];

//Lets say we want to print out "name of dog is size"

//first we create a function to operate on each element of the array

function findSize(x){
return x.name+" is "+x.size;
}

//then we can map each element of the animals array with our function

var [...names] =animals.map( findSize);

console.log(...names);
//"Bailey is small Max is medium Charlie is large Buddy is small "

In ES6 we can use arrow functions to make this look nice and compact

var [...names] =animals.map( x => x.name+" is "+x.size);
console.log(...names);