Object.entries()
Baseline
Ampliamente disponible
Esta característica está consolidada y funciona en muchos dispositivos y versiones de navegador. Está disponible en todos los navegadores desde marzo de 2017.
El método Object.entries() devuelve una matriz de pares propios de una propiedad enumerable [key, value] de un objeto dado, en el mismo orden que es proporcionado por for...in (La diferencia es que un bucle for-in enumera las propiedades en la cadena de prototipos).
Sintaxis
Object.entries(obj)
Parámetros
obj-
The object whose enumerable own property
[key, value]pairs are to be returned.
Valor de retorno
An array of the given object's own enumerable property [key, value] pairs.
Descripción
Object.entries() returns an array whose elements are arrays corresponding to the enumerable property [key, value] pairs found directly upon object. The ordering of the properties is the same as that given by looping over the property values of the object manually.
Ejemplos
var obj = { foo: "bar", baz: 42 };
console.log(Object.entries(obj)); // [ ['foo', 'bar'], ['baz', 42] ]
// array like object
var obj = { 0: "a", 1: "b", 2: "c" };
console.log(Object.entries(obj)); // [ ['0', 'a'], ['1', 'b'], ['2', 'c'] ]
// array like object with random key ordering
var an_obj = { 100: "a", 2: "b", 7: "c" };
console.log(Object.entries(an_obj)); // [ ['2', 'b'], ['7', 'c'], ['100', 'a'] ]
// getFoo is property which isn't enumerable
var my_obj = Object.create(
{},
{
getFoo: {
value: function () {
return this.foo;
},
},
},
);
my_obj.foo = "bar";
console.log(Object.entries(my_obj)); // [ ['foo', 'bar'] ]
// non-object argument will be coerced to an object
console.log(Object.entries("foo")); // [ ['0', 'f'], ['1', 'o'], ['2', 'o'] ]
// iterate through key-value gracefully
var obj = { a: 5, b: 7, c: 9 };
for (var [key, value] of Object.entries(obj)) {
console.log(key + " " + value); // "a 5", "b 7", "c 9"
}
// Or, using array extras
Object.entries(obj).forEach(([key, value]) => {
console.log(key + " " + value); // "a 5", "b 7", "c 9"
});
Converting an Object to a Map
The new Map() constructor accepts an iterable of entries. With Object.entries, you can easily convert from Object to Map:
var obj = { foo: "bar", baz: 42 };
var map = new Map(Object.entries(obj));
console.log(map); // Map { foo: "bar", baz: 42 }
Polyfill
To add compatible Object.entries support in older environments that do not natively support it, you can find a Polyfill in the tc39/proposal-object-values-entries or in the es-shims/Object.entries repositories.
Especificaciones
| Especificación |
|---|
| ECMAScript® 2027 Language Specification # sec-object.entries |