Object.defineProperties()

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Sumario

El metodo Object.defineProperties() define nuevas o modifica propiedades existentes directamente en el objeto, returnando el objeto.

Sintaxis

Object.defineProperties(obj, propiedades)

Parametros

obj
El objeto sobre el cual se crearán o modificaran sus propiedades.
propiedades
An object whose own enumerable properties constitute descriptors for the properties to be defined or modified.

Description

Object.defineProperties, in essence, defines all properties corresponding to the enumerable own properties of props on the object objrops object.

Example

Object.defineProperties(obj, {
  "property1": {
    value: true,
    writable: true
  },
  "property2": {
    value: "Hello",
    writable: false
  }
  // etc. etc.
});

Polyfill

Assuming a pristine execution environment with all names and properties referring to their initial values, Object.defineProperties is almost completely equivalent (note the comment in isCallable) to the following reimplementation in JavaScript:

function defineProperties(obj, properties) {
  function convertToDescriptor(desc) {
    function hasProperty(obj, prop) {
      return Object.prototype.hasOwnProperty.call(obj, prop);
    }

    function isCallable(v) {
      // NB: modify as necessary if other values than functions are callable.
      return typeof v === "function";
    }

    if (typeof desc !== "object" || desc === null)
      throw new TypeError("bad desc");

    var d = {};

    if (hasProperty(desc, "enumerable"))
      d.enumerable = !!obj.enumerable;
    if (hasProperty(desc, "configurable"))
      d.configurable = !!obj.configurable;
    if (hasProperty(desc, "value"))
      d.value = obj.value;
    if (hasProperty(desc, "writable"))
      d.writable = !!desc.writable;
    if ( hasProperty(desc, "get") ) {
      var g = desc.get;

      if (!isCallable(g) && g !== "undefined")
        throw new TypeError("bad get");
      d.get = g;
    }
    if ( hasProperty(desc, "set") ) {
      var s = desc.set;
      if (!isCallable(s) && s !== "undefined")
        throw new TypeError("bad set");
      d.set = s;
    }

    if (("get" in d || "set" in d) && ("value" in d || "writable" in d))
      throw new TypeError("identity-confused descriptor");

    return d;
  }

  if (typeof obj !== "object" || obj === null)
    throw new TypeError("bad obj");

  properties = Object(properties);

  var keys = Object.keys(properties);
  var descs = [];

  for (var i = 0; i < keys.length; i++)
    descs.push([keys[i], convertToDescriptor(properties[keys[i]])]);

  for (var i = 0; i < descs.length; i++)
    Object.defineProperty(obj, descs[i][0], descs[i][1]);

  return obj;
}

Specifications

Specification Status Comment
ECMAScript 5.1 (ECMA-262)
The definition of 'Object.defineProperties' in that specification.
Standard Initial definition.
Implemented in JavaScript 1.8.5
ECMAScript 6 (ECMA-262)
The definition of 'Object.defineProperties' in that specification.
Release Candidate  

Browser compatibility

Based on Kangax's compat tables.

Feature Firefox (Gecko) Chrome Internet Explorer Opera Safari
Basic support 4.0 (2) 5 (previous versions untested) 9 11.60 5
Feature Firefox Mobile (Gecko) Android IE Mobile Opera Mobile Safari Mobile
Basic support 4.0 (2) (Yes) ? 11.50 (Yes)

See also

Etiquetas y colaboradores del documento

Contributors to this page: teoli, guillermojmc
Última actualización por: teoli,
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