map add key to object in array javascript
const newArr = [
{name: 'eve'},
{name: 'john'},
{name: 'jane'}
].map(v => ({...v, isActive: true}))map add key to object in array javascript
const newArr = [
{name: 'eve'},
{name: 'john'},
{name: 'jane'}
].map(v => ({...v, isActive: true}))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 }; });how the map function works javascript
const array = [2, 5, 9];
let squares = array.map((num) => num * num);
console.log(array); // [2, 5, 9]
console.log(squares); // [4, 25, 81]map javascript
var numbers = [1, 4, 9];
var doubles = numbers.map(function(num) {
return num * 2;
});
// doubles is now [2, 8, 18]. numbers still [1, 4, 9]javascript map array
const sweetArray = [2, 3, 4, 5, 35]
const sweeterArray = sweetArray.map(sweetItem => {
return sweetItem * 2
})
console.log(sweeterArray)map in javascript
let myMap = new Map()
let keyString = 'a string'
let keyObj = {}
// setting the values
myMap.set(keyString, "value associated with 'a string'")
myMap.set(keyObj, 'value associated with keyObj')
myMap.set(keyFunc, 'value associated with keyFunc')
myMap.size // 3
// getting the values
myMap.get(keyString) // "value associated with 'a string'"
myMap.get(keyObj) // "value associated with keyObj"
myMap.get(keyFunc) // "value associated with keyFunc"Copyright © 2021 Codeinu
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