Map in java script code example

Example 1: javascript map function

const posts = [
  { id: 1, title: "Sample Title 1", description: "Lorem ipsum dolor sit amet, consectetur adipiscing elit..." },
  { id: 2, title: "Sample Title 2", description: "Lorem ipsum dolor sit amet, consectetur adipiscing elit..." },
  { id: 3, title: "Sample Title 3", description: "Lorem ipsum dolor sit amet, consectetur adipiscing elit..." },
];
// ES2016+
// Create new array of post IDs. I.e. [1,2,3]
const postIds = posts.map((post) => post.id);
// Create new array of post objects. I.e. [{ id: 1, title: "Sample Title 1" }]
const postSummaries = posts.map((post) => ({ id: post.id, title: post.title }));

// ES2015
// Create new array of post IDs. I.e. [1,2,3]
var postIds = posts.map(function (post) { return post.id; });
// Create new array of post objects. I.e. [{ id: 1, title: "Sample Title 1" }]
var postSummaries = posts.map(function (post) { return { id: post.id, title: post.title }; });

Example 2: javascript map

function listFruits() {
  let fruits = ["apple", "cherry", "pear"]
  
  fruits.map((fruit, index) => {
    console.log(index, fruit)
  })
}

listFruits()

// https://jsfiddle.net/tmoreland/16qfpkgb/3/

Example 3: map in js

//map() methods returns a new array
const data = {name: "laptop", brands: ["dell", "acer", "asus"]}
let inside_data = data.brands.map((i) => {
	console.log(i); //dell acer asus
});

Example 4: javascript map

array.map( item => item.id )

array2.map( item => item.toString() )

array2.map( item => item * 3 )

// this will apply a transformation to all elements of an array
// "" item => something "" is the transformation (function)