map to array javascript
let map = new Map().set('a', 1).set('b', 2),
array = Array.from(map, ([name, value]) => ({ name, value }));
console.log(array);map to array javascript
let map = new Map().set('a', 1).set('b', 2),
array = Array.from(map, ([name, value]) => ({ name, value }));
console.log(array);array map
let numbers = [1, 2, 3, 4]
let filteredNumbers = numbers.map(function(_, index) {
if (index < 3) {
return num
}
})
// index goes from 0, so the filterNumbers are 1,2,3 and undefined.
// filteredNumbers is [1, 2, 3, undefined]
// numbers is still [1, 2, 3, 4]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.map javascript
function map(collection, action) {
let result = [];
if (Array.isArray(collection)) {
for (let i = 0; i < collection.length; i++) {
result.push(action(collection[i], i, collection));
}
}
else {
for (let key in collection) {
result.push(action(collection[key], key, collection));
}
} return result;
}Copyright © 2021 Codeinu
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