In JS map it is responsible for generating a response array from a function applied to an input array
Basically it allows you to loop through an object and/or an array of objects in a new item.
Basically it allows you to loop through an object and/or an array of objects in a new item.
Iterates through an object but returns numbers different from the original object
map allows you to manipulate an array response more efficiently without having to normally generate loops and whiles to iterate through all the vector items
CREATE A NEW ARRANGE STARTED WITH ANOTHER
acts as a for
In a nutshell, it walks through the placed array.
In more descriptive terms it creates a new array with the results applied in the method.
Example:
We are going to map an array to find the numbers greater than 2.
we have our first array that we will call array1
array1 = [1, 2, 3, 4]To create the map method is as follows:
yourArray.map (receivesAnItem => returnsTheResultAppliedToYourElements)
So we're going to use the map method to find out which numbers are greater than 2.
newArray = array1.map(num => num > 2)This would return:
console.log(newArray); result: [false, false, true, true]In cases more developed in the labor field, it is used a lot for JSON, such as:
myJson = [ { "name": "Pepito", "age": 20, }, { "name": "Juan", "age": 28 } ]Let's map this JSON to get the names.
newJson = myJson.map(item => item.name)This would return a new array with the elements that would be the names.
console.log(newJson); result: ['Pepito', 'Juan']It goes through an array and returns a new one, with the result of the operations or processes applied to each item of the collection.
The map method in Javascript allows us to use an array to create a new one, which is the result of the return of a function that we pass as an argument, in said function we can do any process on each element of the array, to then return an element that will be part of the new array.
let nums = [1,5,6,8,7] let powOddNums = nums.map(function(element){ if(element % 2 !== 0 ){ return element * element } return element }) result: [1,25,6,8,49]The textual definition indicates that it creates a new array from an existing one, but this relative to what we do in the callback function is passed as an argument, you can even use the map without taking the result to a variable (myArray.map(element => {only view element})).
In conclusion, the map method loops through an array, extracting each element of an existing array in order.
The Map object holds key-value pairs and remembers the original insertion order of the keys. Any value (both objects and primitive values) may be used as either a key or a value.
A Map object iterates its elements in insertion order — a for...of loop returns an array of [key, value] for each iteration.
Object is similar to Map—both let you set keys to values, retrieve those values, delete keys, and detect whether something is stored at a key. For this reason (and because there were no built-in alternatives), Object has been used as Map historically.
However, there are important differences that make Map preferable in some cases:
If you want to learn more about map of javascript, please read this article.....
Good Luck...