path: root/files/he/web/javascript/reference/global_objects/object/assign/index.html

---
title: Object.assign()
slug: Web/JavaScript/Reference/Global_Objects/Object/assign
translation_of: Web/JavaScript/Reference/Global_Objects/Object/assign
---
<p>{{JSRef}}</p>

<p dir="rtl">מתודת <span class="seoSummary"><strong><code>Object.assign</code> מעתיקה אובייקט על שלל </strong>{{jsxref("Object/propertyIsEnumerable", "מאפייניו", "", 1)} {{jsxref("Object/hasOwnProperty", "הקיימים", "", 1)}} לאובייקט אחר וממזגת אותם ביחד. המתודה מחזירה את האובייקט שאליו העתקנו את התכונות החדשות. </span></p>

<div dir="rtl">תחביר</div>

<pre class="syntaxbox notranslate">Object.assign(<var>target</var>, ...<var>sources</var>)</pre>

<h3 dir="rtl" id="פרמטרים">פרמטרים</h3>

<dl>
 <dt dir="rtl"><code><var>target - אובייקט היעד</var></code></dt>
 <dd dir="rtl">אובייקט היעד- האובייקט שאליו אנחנו מעתיקים את כל המאפיינים של האובייקט המקורי, כאשר הוא מחזיר את האובייקט אחרי המיזוג.</dd>
 <dt dir="rtl"><code><var>sources - אובייקט המקור</var></code></dt>
 <dd></dd>
</dl>

<dl>
 <dd dir="rtl">אובייקט המקור - האובייקט מכיל את המאפיינים שאנחנו רוצים להעתיק לאובייקט נוסף. </dd>
</dl>

<h3 dir="rtl" id="Return_value_-_הנתון_התוצאה">Return value - הנתון התוצאה</h3>

<p dir="rtl">The target object - האובייקט שאליו העתקנו את התכונות של האובייקט המקורי.</p>

<h2 dir="rtl" id="תיאור">תיאור</h2>

<p dir="rtl">מאפיינים באובייקט היעד ישוכתבו או ידרסו ע"י המאפיינים של אובייקט המקור אם הם חולקים את אותו ה-{{jsxref("Object/keys", "key", "", 1)}}. מאפיינים חדשים שיוגדו על מאפיינים משותפים (properties) בהמשך ידרסו גם באובייקט היעד וגם באופייקט המקור.</p>

<p dir="rtl"></p>

<p>The <code>Object.assign()</code> method only copies <em>enumerable</em> and <em>own</em> properties from a source object to a target object. It uses <code>[[Get]]</code> on the source and <code>[[Set]]</code> on the target, so it will invoke <a href="/en-US/docs/Web/JavaScript/Reference/Functions/get">getters</a> and <a href="/en-US/docs/Web/JavaScript/Reference/Functions/set">setters</a>. Therefore it <em>assigns</em> properties, versus copying or defining new properties. This may make it unsuitable for merging new properties into a prototype if the merge sources contain getters.</p>

<p>For copying property definitions (including their enumerability) into prototypes, use {{jsxref("Object.getOwnPropertyDescriptor()")}} and {{jsxref("Object.defineProperty()")}} instead.</p>

<p>Both {{jsxref("String")}} and {{jsxref("Symbol")}} properties are copied.</p>

<p>In case of an error, for example if a property is non-writable, a {{jsxref("TypeError")}} is raised, and the <code><var>target</var></code> object is changed if any properties are added before the error is raised.</p>

<div class="blockIndicator note">
<p><strong>Note:</strong> <code>Object.assign()</code> does not throw on {{jsxref("null")}} or {{jsxref("undefined")}} sources.</p>
</div>

<h2 id="Polyfill">Polyfill</h2>

<p>This <a href="/en-US/docs/Glossary/Polyfill">polyfill</a> doesn't support symbol properties, since ES5 doesn't have symbols anyway:</p>

<pre class="brush: js notranslate">if (typeof Object.assign !== 'function') {
  // Must be writable: true, enumerable: false, configurable: true
  Object.defineProperty(Object, "assign", {
    value: function assign(target, varArgs) { // .length of function is 2
      'use strict';
      if (target === null || target === undefined) {
        throw new TypeError('Cannot convert undefined or null to object');
      }

      var to = Object(target);

      for (var index = 1; index &lt; arguments.length; index++) {
        var nextSource = arguments[index];

        if (nextSource !== null &amp;&amp; nextSource !== undefined) {
          for (var nextKey in nextSource) {
            // Avoid bugs when hasOwnProperty is shadowed
            if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
              to[nextKey] = nextSource[nextKey];
            }
          }
        }
      }
      return to;
    },
    writable: true,
    configurable: true
  });
}
</pre>

<h2 id="Examples">Examples</h2>

<h3 id="Cloning_an_object">Cloning an object</h3>

<pre class="brush: js notranslate">const obj = { a: 1 };
const copy = Object.assign({}, obj);
console.log(copy); // { a: 1 }
</pre>

<h3 id="Deep_Clone" name="Deep_Clone">Warning for Deep Clone</h3>

<p>For deep cloning, we need to use alternatives, because <code>Object.assign()</code> copies property values.</p>

<p>If the source value is a reference to an object, it only copies the reference value.</p>

<pre class="brush: js notranslate">function test() {
  'use strict';

  let obj1 = { a: 0 , b: { c: 0}};
  let obj2 = Object.assign({}, obj1);
  console.log(JSON.stringify(obj2)); // { "a": 0, "b": { "c": 0}}

  obj1.a = 1;
  console.log(JSON.stringify(obj1)); // { "a": 1, "b": { "c": 0}}
  console.log(JSON.stringify(obj2)); // { "a": 0, "b": { "c": 0}}

  obj2.a = 2;
  console.log(JSON.stringify(obj1)); // { "a": 1, "b": { "c": 0}}
  console.log(JSON.stringify(obj2)); // { "a": 2, "b": { "c": 0}}

  obj2.b.c = 3;
  console.log(JSON.stringify(obj1)); // { "a": 1, "b": { "c": 3}}
  console.log(JSON.stringify(obj2)); // { "a": 2, "b": { "c": 3}}

  // Deep Clone
  obj1 = { a: 0 , b: { c: 0}};
  let obj3 = JSON.parse(JSON.stringify(obj1));
  obj1.a = 4;
  obj1.b.c = 4;
  console.log(JSON.stringify(obj3)); // { "a": 0, "b": { "c": 0}}
}

test();</pre>

<h3 id="Merging_objects">Merging objects</h3>

<pre class="brush: js notranslate">const o1 = { a: 1 };
const o2 = { b: 2 };
const o3 = { c: 3 };

const obj = Object.assign(o1, o2, o3);
console.log(obj); // { a: 1, b: 2, c: 3 }
console.log(o1);  // { a: 1, b: 2, c: 3 }, target object itself is changed.</pre>

<h3 id="Merging_objects_with_same_properties">Merging objects with same properties</h3>

<pre class="brush: js notranslate">const o1 = { a: 1, b: 1, c: 1 };
const o2 = { b: 2, c: 2 };
const o3 = { c: 3 };

const obj = Object.assign({}, o1, o2, o3);
console.log(obj); // { a: 1, b: 2, c: 3 }</pre>

<p>The properties are overwritten by other objects that have the same properties later in the parameters order.</p>

<h3 id="Copying_symbol-typed_properties">Copying symbol-typed properties</h3>

<pre class="brush: js notranslate">const o1 = { a: 1 };
const o2 = { [Symbol('foo')]: 2 };

const obj = Object.assign({}, o1, o2);
console.log(obj); // { a : 1, [Symbol("foo")]: 2 } (cf. bug 1207182 on Firefox)
Object.getOwnPropertySymbols(obj); // [Symbol(foo)]
</pre>

<h3 id="Properties_on_the_prototype_chain_and_non-enumerable_properties_cannot_be_copied">Properties on the prototype chain and non-enumerable properties cannot be copied</h3>

<pre class="brush: js notranslate">const obj = Object.create({ foo: 1 }, { // foo is on obj's prototype chain.
  bar: {
    value: 2  // bar is a non-enumerable property.
  },
  baz: {
    value: 3,
    enumerable: true  // baz is an own enumerable property.
  }
});

const copy = Object.assign({}, obj);
console.log(copy); // { baz: 3 }
</pre>

<h3 id="Primitives_will_be_wrapped_to_objects">Primitives will be wrapped to objects</h3>

<pre class="brush: js notranslate">const v1 = 'abc';
const v2 = true;
const v3 = 10;
const v4 = Symbol('foo');

const obj = Object.assign({}, v1, null, v2, undefined, v3, v4);
// Primitives will be wrapped, null and undefined will be ignored.
// Note, only string wrappers can have own enumerable properties.
console.log(obj); // { "0": "a", "1": "b", "2": "c" }
</pre>

<h3 id="Exceptions_will_interrupt_the_ongoing_copying_task">Exceptions will interrupt the ongoing copying task</h3>

<pre class="brush: js notranslate">const target = Object.defineProperty({}, 'foo', {
  value: 1,
  writable: false
}); // target.foo is a read-only property

Object.assign(target, { bar: 2 }, { foo2: 3, foo: 3, foo3: 3 }, { baz: 4 });
// TypeError: "foo" is read-only
// The Exception is thrown when assigning target.foo

console.log(target.bar);  // 2, the first source was copied successfully.
console.log(target.foo2); // 3, the first property of the second source was copied successfully.
console.log(target.foo);  // 1, exception is thrown here.
console.log(target.foo3); // undefined, assign method has finished, foo3 will not be copied.
console.log(target.baz);  // undefined, the third source will not be copied either.
</pre>

<h3 id="Copying_accessors">Copying accessors</h3>

<pre class="brush: js notranslate">const obj = {
  foo: 1,
  get bar() {
    return 2;
  }
};

let copy = Object.assign({}, obj);
console.log(copy);
// { foo: 1, bar: 2 }
// The value of copy.bar is obj.bar's getter's return value.

// This is an assign function that copies full descriptors
function completeAssign(target, ...sources) {
  sources.forEach(source =&gt; {
    let descriptors = Object.keys(source).reduce((descriptors, key) =&gt; {
      descriptors[key] = Object.getOwnPropertyDescriptor(source, key);
      return descriptors;
    }, {});

    // By default, Object.assign copies enumerable Symbols, too
    Object.getOwnPropertySymbols(source).forEach(sym =&gt; {
      let descriptor = Object.getOwnPropertyDescriptor(source, sym);
      if (descriptor.enumerable) {
        descriptors[sym] = descriptor;
      }
    });
    Object.defineProperties(target, descriptors);
  });
  return target;
}

copy = completeAssign({}, obj);
console.log(copy);
// { foo:1, get bar() { return 2 } }
</pre>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-object.assign', 'Object.assign')}}</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>



<p>{{Compat("javascript.builtins.Object.assign")}}</p>

<h2 id="See_also">See also</h2>

<ul>
 <li>{{jsxref("Object.defineProperties()")}}</li>
 <li><a href="/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties">Enumerability and ownership of properties</a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax#Spread_in_object_literals">Spread in object literals</a></li>
</ul>