isEmptyObject()?jQuery.isEmptyObject(object) (alias $.isEmptyObject) returns true when the object has no enumerable properties (since jQuery 1.4). Empty {} is true; any key makes it false.
$.isEmptyObject(object) → true | false
$.isEmptyObject({}) // true
$.isEmptyObject({ foo: "bar" }) // false
// Official guidance: plain objects only
$.isPlainObject(obj) && $.isEmptyObject(obj)| Need | Use |
|---|---|
| No enumerable keys? | $.isEmptyObject(obj) |
| Is it a plain object? | $.isPlainObject(obj) |
| Own keys only (native) | Object.keys(obj).length === 0 |
| Merge defaults | $.extend({}, defaults, opts) |
isEmptyObject()Pass a plain object, then branch on empty vs has keys.
$.isPlainObject(obj).$.isEmptyObject(obj).true, treat as “no settings”; if false, read or merge the keys.| Piece | Required? | Role |
|---|---|---|
object | Yes | Plain object to test |
| Return | — | Boolean |
| Since 1.4 | — | Also sees inherited enumerable props |
function isEmptyObject(object):
for each enumerable key in object: // for...in
return false
return true
// Typical options pattern:
if isEmptyObject(userOptions):
settings = defaults
else:
settings = extend({}, defaults, userOptions)Keep these facts handy while checking empty objects.
| Topic | Detail |
|---|---|
| Syntax | jQuery.isEmptyObject(object) |
| Since | jQuery 1.4 |
| Empty | {} → true |
| Has keys | { foo: "bar" } → false |
| Input | Plain object (recommended) |
| vs Object.keys | Own props only vs for...in (incl. inherited) |
| Pair with | $.isPlainObject() |
Test a few plain objects with $.isEmptyObject.
Short, copy-ready snippets. Open DevTools Console, or use Try It Yourself for a live editor.
The classic true/false pair from the jQuery docs.
console.log($.isEmptyObject({})); // true
console.log($.isEmptyObject({ foo: "bar" })); // false{} has no enumerable keys → true.foo is enumerable → false.if guards.Skip merging when the caller passed {}.
var defaults = { theme: "light", size: 16 };
var userOptions = {};
var settings;
if ($.isEmptyObject(userOptions)) {
settings = defaults;
} else {
settings = $.extend({}, defaults, userOptions);
}
console.log(settings.theme); // "light"userOptions is {} → isEmptyObject is true.defaults directly.$.extend when options have keys.Object.keysOwn-property count is a common native twin.
var a = {};
var b = { x: 1 };
console.log($.isEmptyObject(a)); // true
console.log(Object.keys(a).length === 0); // true
console.log($.isEmptyObject(b)); // false
console.log(Object.keys(b).length === 0); // false{} and { x: 1 }.for...in (can include inherited enumerable keys).Object.keys when you only care about own keys.isPlainObjectFollow the docs: confirm “plain object” before the empty check.
function isEmptyPlain(obj) {
return $.isPlainObject(obj) && $.isEmptyObject(obj);
}
console.log(isEmptyPlain({})); // true
console.log(isEmptyPlain({ a: 1 })); // false
console.log(isEmptyPlain([])); // false (not plain object)$.isPlainObject rejects arrays and host objects.$.isEmptyObject checks for enumerable keys.{} (and similar) returns true.[] fails the plain-object test → false.Check these before trusting empty-object results.
DOM elements, strings, and host objects may not be consistent across browsers. Pair with $.isPlainObject().
null / undefined can throwNormalize first: var opts = options || {}, then call $.isEmptyObject(opts).
{ user: {} } has a key — result is false. Empty means no enumerable keys at that object level.
Since 1.4, for...in can see prototype properties. For own keys only, use Object.keys(obj).length === 0.
jQuery.isEmptyObject() is available since jQuery 1.4+ in all browsers that load jQuery. It is a data utility — no special DOM API required.
Works wherever jQuery runs in the browser. For own-property checks without jQuery, use Object.keys(obj).length === 0 on plain objects.
Bottom line: Use $.isEmptyObject(obj) on plain objects in jQuery apps. Prefer Object.keys when you only need own properties.
| Approach | Cost | Best for |
|---|---|---|
$.isEmptyObject(obj) | O(k) keys seen | Empty checks in jQuery code |
Object.keys(obj).length === 0 | O(n) own keys | Own-property emptiness |
| Skip check + always extend | Extra work | Tiny option objects (usually fine) |
Option objects are usually tiny. Prefer clear guards over micro-optimizing emptiness checks.
$.isEmptyObject(obj) → no enumerable keys.isPlainObject.{} true · { foo: "bar" } false.Object.keys when that is all you need.One line: use $.isEmptyObject on plain objects to detect “no settings” — confirm plain first, and normalize null/undefined.
Learn how jQuery tests whether a value is a callable function.
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