js map constructor
let myMap = new Map([
[1, 'one'], // [key, value]
[2, 'two'],
[3, 'three'],
]) // from MDNjs map constructor
let myMap = new Map([
[1, 'one'], // [key, value]
[2, 'two'],
[3, 'three'],
]) // from MDNjavascript 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 }; });array map javascript
const array1 = [1, 4, 9, 16];
// pass a function to map
const map1 = array1.map(x => x * 2);
console.log(map1);
// expected output: Array [2, 8, 18, 32]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
});map javascript
var miMapa = new Map();
var claveObj = {},
claveFunc = function () {},
claveCadena = "una cadena";
// asignando valores
miMapa.set(claveCadena, "valor asociado con 'una cadena'");
miMapa.set(claveObj, "valor asociado con claveObj");
miMapa.set(claveFunc, "valor asociado with claveFunc");
miMapa.size; // 3
// obteniendo los valores
miMapa.get(claveCadena); // "valor asociado con 'una cadena'"
miMapa.get(claveObj); // "valor asociado con claveObj"
miMapa.get(claveFunc); // "valor asociado con claveFunc"
miMapa.get("una cadena"); // ""valor asociado con 'una cadena'"
// porque claveCadena === 'una cadena'
miMapa.get({}); // undefined, porque claveObj !== {}
miMapa.get(function() {}) // undefined, porque claveFunc !== function () {}
var myMap = new Map();
myMap.set("bar", "foo");
myMap.delete("bar"); // Retorna true. Eliminado con éxito.
myMap.has("bar"); // Retorna false. El elemento "bar" ya no está presente.Copyright © 2021 Codeinu
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