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---
title: Object.getOwnPropertyNames()
slug: Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames
translation_of: Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames
---
<div>{{JSRef}}</div>
<p>The <strong><code>Object.getOwnPropertyNames()</code></strong> phuong thuc nay tra ve mang (including non-enumerable properties except for those which use Symbol) found directly in a given object.</p>
<div>{{EmbedInteractiveExample("pages/js/object-getownpropertynames.html")}}</div>
<h2 id="Syntax">Syntax</h2>
<pre class="brush: js">Object.getOwnPropertyNames(<var>obj</var>)</pre>
<h3 id="Parameters">Parameters</h3>
<dl>
<dt><code><var>obj</var></code></dt>
<dd>The object whose enumerable and non-enumerable properties are to be returned.</dd>
</dl>
<h3 id="Return_value">Return value</h3>
<p>An array of strings that corresponds to the properties found directly in the given object.</p>
<h2 id="Description">Description</h2>
<p><code>Object.getOwnPropertyNames()</code> returns an array whose elements are strings corresponding to the enumerable and non-enumerable properties found directly in a given object <code><var>obj</var></code>. The ordering of the enumerable properties in the array is consistent with the ordering exposed by a {{jsxref("Statements/for...in", "for...in")}} loop (or by {{jsxref("Object.keys()")}}) over the properties of the object. The ordering of the non-enumerable properties in the array and the ordering among the enumerable properties is not defined.</p>
<h2 id="Examples">Examples</h2>
<h3 id="Using_Object.getOwnPropertyNames">Using <code>Object.getOwnPropertyNames()</code></h3>
<pre class="brush: js">var arr = ['a', 'b', 'c'];
console.log(Object.getOwnPropertyNames(arr).sort());
// logs ["0", "1", "2", "length"]
// Array-like object
var obj = { 0: 'a', 1: 'b', 2: 'c' };
console.log(Object.getOwnPropertyNames(obj).sort());
// logs ["0", "1", "2"]
// Logging property names and values using Array.forEach
Object.getOwnPropertyNames(obj).forEach(
function (val, idx, array) {
console.log(val + ' -> ' + obj[val]);
}
);
// logs
// 0 -> a
// 1 -> b
// 2 -> c
// non-enumerable property
var my_obj = Object.create({}, {
getFoo: {
value: function() { return this.foo; },
enumerable: false
}
});
my_obj.foo = 1;
console.log(Object.getOwnPropertyNames(my_obj).sort());
// logs ["foo", "getFoo"]
</pre>
<p>If you want only the enumerable properties, see {{jsxref("Object.keys()")}} or use a {{jsxref("Statements/for...in", "for...in")}} loop (note that this will also return enumerable properties found along the prototype chain for the object unless the latter is filtered with {{jsxref("Object.prototype.hasOwnProperty()", "hasOwnProperty()")}}).</p>
<p>Items on the prototype chain are not listed:</p>
<pre class="brush: js">function ParentClass() {}
ParentClass.prototype.inheritedMethod = function() {};
function ChildClass() {
this.prop = 5;
this.method = function() {};
}
ChildClass.prototype = new ParentClass;
ChildClass.prototype.prototypeMethod = function() {};
console.log(
Object.getOwnPropertyNames(
new ChildClass() // ["prop", "method"]
)
);
</pre>
<h3 id="Get_non-enumerable_properties_only">Get non-enumerable properties only</h3>
<p>This uses the {{jsxref("Array.prototype.filter()")}} function to remove the enumerable keys (obtained with {{jsxref("Object.keys()")}}) from a list of all keys (obtained with <code>Object.getOwnPropertyNames()</code>) thus giving only the non-enumerable keys as output.</p>
<pre class="brush: js">var target = myObject;
var enum_and_nonenum = Object.getOwnPropertyNames(target);
var enum_only = Object.keys(target);
var nonenum_only = enum_and_nonenum.filter(function(key) {
var indexInEnum = enum_only.indexOf(key);
if (indexInEnum == -1) {
// Not found in enum_only keys,
// meaning that the key is non-enumerable,
// so return true so we keep this in the filter
return true;
} else {
return false;
}
});
console.log(nonenum_only);
</pre>
<h2 id="Notes">Notes</h2>
<p>In ES5, if the argument to this method is not an object (a primitive), then it will cause a {{jsxref("TypeError")}}. In ES2015, a non-object argument will be coerced to an object.</p>
<pre class="brush: js">Object.getOwnPropertyNames('foo');
// TypeError: "foo" is not an object (ES5 code)
Object.getOwnPropertyNames('foo');
// ["0", "1", "2", "length"] (ES2015 code)
</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.getownpropertynames', 'Object.getOwnPropertyNames')}}</td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility">Browser compatibility</h2>
<p>{{Compat("javascript.builtins.Object.getOwnPropertyNames")}}</p>
<h2 id="Firefox-specific_notes">Firefox-specific notes</h2>
<p>Prior to Firefox 28, <code>Object.getOwnPropertyNames</code> did not see unresolved properties of {{jsxref("Error")}} objects. This has been fixed in later versions (<a href="https://bugzilla.mozilla.org/show_bug.cgi?id=724768">bug 724768</a>).</p>
<h2 id="See_also">See also</h2>
<ul>
<li><a href="/en-US/docs/Enumerability_and_ownership_of_properties">Enumerability and ownership of properties</a></li>
<li>{{jsxref("Object.prototype.hasOwnProperty()")}}</li>
<li>{{jsxref("Object.prototype.propertyIsEnumerable()")}}</li>
<li>{{jsxref("Object.create()")}}</li>
<li>{{jsxref("Object.keys()")}}</li>
<li>{{jsxref("Array.forEach()")}}</li>
</ul>
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