After an AJAX request, sometimes my application may return an empty object, like:
var a = {};
How can I check whether that's the case?
This question is related to
javascript
javascript-objects
The answer is
This is what I came up with, to tell if there are any non-null values in the object.
function isEmpty(obj: Object): Boolean {
for (const prop in obj) {
if (obj.hasOwnProperty(prop)) {
if (obj[prop] instanceof Object) {
const rtn = this.isEmpty(obj[prop]);
if (rtn === false) {
return false;
}
} else if (obj[prop] || obj[prop] === false) {
return false;
}
}
}
return true;
}
The correct answer is:
const isEmptyObject = obj =>
Object.getOwnPropertyNames(obj).length === 0 &&
Object.getOwnPropertySymbols(obj).length === 0 &&
Object.getPrototypeOf(obj) === Object.prototype;
This checks that:
- The object has no own properties (regardless of enumerability).
- The object has no own property symbols.
- The object's prototype is exactly
Object.prototype.
In other words, the object is indistinguishable from one created with {}.
In addition to Thevs answer:
var o = {};
alert($.toJSON(o)=='{}'); // true
var o = {a:1};
alert($.toJSON(o)=='{}'); // false
it's jquery + jquery.json
Mostly what you want to know is, if the object has properties before using it. So instead of asking isEmpty and then always check the negation like if(!isEmpty(obj)) you can just test if the object is not null and has properties instead
export function hasProperties(obj): boolean {
return obj && obj.constructor === Object && Object.keys(obj).length >= 1;
}
you can use this simple code that did not use jQuery or other libraries
var a=({});
//check is an empty object
if(JSON.stringify(a)=='{}') {
alert('it is empty');
} else {
alert('it is not empty');
}
JSON class and it's functions (parse and stringify) are very usefull but has some problems with IE7 that you can fix it with this simple code http://www.json.org/js.html.
Other Simple Way (simplest Way) :
you can use this way without using jQuery or JSON object.
var a=({});
function isEmptyObject(obj) {
if(typeof obj!='object') {
//it is not object, so is not empty
return false;
} else {
var x,i=0;
for(x in obj) {
i++;
}
if(i>0) {
//this object has some properties or methods
return false;
} else {
//this object has not any property or method
return true;
}
}
}
alert(isEmptyObject(a)); //true is alerted
As per the ES2017 specification on Object.entries(), the check is simple using any modern browser--
Object.entries({}).length === 0
I just ran into a similar situation. I didn't want to use JQuery, and wanted to do this using pure Javascript.
And what I did was, used the following condition, and it worked for me.
var obj = {};
if(JSON.stringify(obj) === '{}') { //This will check if the object is empty
//Code here..
}
For not equal to, use this : JSON.stringify(obj) !== '{}'
Check out this JSFiddle
Best way that I found:
function isEmpty(obj)
{
if (!obj)
{
return true;
}
if (!(typeof(obj) === 'number') && !Object.keys(obj).length)
{
return true;
}
return false;
}
Works for:
t1: {} -> true
t2: {0:1} -: false
t3: [] -> true
t4: [2] -> false
t5: null -> true
t6: undefined -> true
t7: "" -> true
t8: "a" -> false
t9: 0 -> true
t10: 1 -> false
Performance
Today 2020.01.17 I perform tests on MacOs HighSierra 10.13.6 on Chrome v79.0, Safari v13.0.4 and Firefox v72.0, for chosen solutions.
Conclusions
- solutions based on
for-in(A,J,L,M) are fastest - solutions based on
JSON.stringify(B,K) are slow - surprisingly also solution based on
Object(N) is slow
Details
Below in snippet are presented 15 solutions. If you want to run performance test on your machine click HERE.
var log = (s,f) => console.log(`${s} --> {}:${f({})} {k:2}:${f({k:2})}`);_x000D_
_x000D_
function A(obj) {_x000D_
for(var i in obj) return false; _x000D_
return true;_x000D_
}_x000D_
_x000D_
function B(obj) {_x000D_
return JSON.stringify(obj) === '{}';_x000D_
}_x000D_
_x000D_
function C(obj) {_x000D_
return Object.keys(obj).length === 0;_x000D_
}_x000D_
_x000D_
function D(obj) {_x000D_
return Object.entries(obj).length === 0;_x000D_
}_x000D_
_x000D_
function E(obj) {_x000D_
return Object.getOwnPropertyNames(obj).length === 0;_x000D_
}_x000D_
_x000D_
function F(obj) {_x000D_
return Object.keys(obj).length === 0 && obj.constructor === Object;_x000D_
}_x000D_
_x000D_
function G(obj) {_x000D_
return typeof obj === "undefined" || !Boolean(Object.keys(obj)[0]);_x000D_
}_x000D_
_x000D_
function H(obj) {_x000D_
return Object.entries(obj).length === 0 && obj.constructor === Object;_x000D_
}_x000D_
_x000D_
function I(obj) {_x000D_
return Object.values( obj ).every( val => typeof val === "undefined" );_x000D_
}_x000D_
_x000D_
function J(obj) {_x000D_
for (const key in obj) {_x000D_
if (hasOwnProperty.call(obj, key)) {_x000D_
return false_x000D_
}_x000D_
}_x000D_
return true;_x000D_
}_x000D_
_x000D_
function K(obj) {_x000D_
for(var prop in obj) {_x000D_
if(obj.hasOwnProperty(prop)) {_x000D_
return false;_x000D_
}_x000D_
}_x000D_
_x000D_
return JSON.stringify(obj) == JSON.stringify({});_x000D_
}_x000D_
_x000D_
function L(obj) {_x000D_
for(var prop in obj) {_x000D_
if(obj.hasOwnProperty(prop))_x000D_
return false;_x000D_
}_x000D_
_x000D_
return true;_x000D_
}_x000D_
_x000D_
function M(obj) {_x000D_
for (var k in obj)_x000D_
{ _x000D_
if ( obj.hasOwnProperty(k) )_x000D_
{ _x000D_
return false;_x000D_
} _x000D_
}_x000D_
return true; _x000D_
}_x000D_
_x000D_
function N(obj) {_x000D_
return Object.getOwnPropertyNames(obj).length === 0 &&_x000D_
Object.getOwnPropertySymbols(obj).length === 0 &&_x000D_
Object.getPrototypeOf(obj) === Object.prototype; _x000D_
}_x000D_
_x000D_
function O(obj) {_x000D_
return !(Object.getOwnPropertyNames != undefined ? Object.getOwnPropertyNames(obj).length != 0 : (function(){for(var key in obj) break; return (key != null) && (key != undefined);})())_x000D_
}_x000D_
_x000D_
log('A',A);_x000D_
log('B',B);_x000D_
log('C',C);_x000D_
log('D',D);_x000D_
log('E',E);_x000D_
log('F',F);_x000D_
log('G',G);_x000D_
log('H',H);_x000D_
log('I',I);_x000D_
log('J',J);_x000D_
log('K',K);_x000D_
log('L',L);_x000D_
log('M',M);_x000D_
log('N',N);_x000D_
log('O',O);
Using Object.keys(obj).length (as suggested above for ECMA 5+) is 10 times slower for empty objects! keep with the old school (for...in) option.
Tested under Node, Chrome, Firefox and IE 9, it becomes evident that for most use cases:
- (for...in...) is the fastest option to use!
- Object.keys(obj).length is 10 times slower for empty objects
- JSON.stringify(obj).length is always the slowest (not suprising)
- Object.getOwnPropertyNames(obj).length takes longer than Object.keys(obj).length can be much longer on some systems.
Bottom line performance wise, use:
function isEmpty(obj) {
for (var x in obj) { return false; }
return true;
}
or
function isEmpty(obj) {
for (var x in obj) { if (obj.hasOwnProperty(x)) return false; }
return true;
}
See detailed testing results and test code at Is object empty?
Pure Vanilla Javascript, and full backward compatibility
function isObjectDefined (Obj) {_x000D_
if (Obj === null || typeof Obj !== 'object' ||_x000D_
Object.prototype.toString.call(Obj) === '[object Array]') {_x000D_
return false_x000D_
} else {_x000D_
for (var prop in Obj) {_x000D_
if (Obj.hasOwnProperty(prop)) {_x000D_
return true_x000D_
}_x000D_
}_x000D_
return JSON.stringify(Obj) !== JSON.stringify({})_x000D_
}_x000D_
}_x000D_
_x000D_
console.log(isObjectDefined()) // false_x000D_
console.log(isObjectDefined('')) // false_x000D_
console.log(isObjectDefined(1)) // false_x000D_
console.log(isObjectDefined('string')) // false_x000D_
console.log(isObjectDefined(NaN)) // false_x000D_
console.log(isObjectDefined(null)) // false_x000D_
console.log(isObjectDefined({})) // false_x000D_
console.log(isObjectDefined([])) // false_x000D_
console.log(isObjectDefined({a: ''})) // trueisEmpty for value any type
/* eslint-disable no-nested-ternary */
const isEmpty = value => {
switch (typeof value) {
case 'undefined':
return true;
case 'object':
return value === null
? true
: Array.isArray(value)
? !value.length
: Object.entries(value).length === 0 && value.constructor === Object;
case 'string':
return !value.length;
default:
return false;
}
};
You could check for the count of the Object keys:
if (Object.keys(a).length > 0) {
// not empty
}
I know this doesn't answer 100% your question, but I have faced similar issues before and here's how I use to solve them:
I have an API that may return an empty object. Because I know what fields to expect from the API, I only check if any of the required fields are present or not.
For example:
API returns {} or {agentID: '1234' (required), address: '1234 lane' (opt),...}.
In my calling function, I'll only check
if(response.data && response.data.agentID) {
do something with my agentID
} else {
is empty response
}
This way I don't need to use those expensive methods to check if an object is empty. The object will be empty for my calling function if it doesn't have the agentID field.
Best one-liner solution I could find (updated):
isEmpty = obj => !Object.values(obj).filter(e => typeof e !== 'undefined').length;
console.log(isEmpty({})) // true
console.log(isEmpty({a: undefined, b: undefined})) // true
console.log(isEmpty({a: undefined, b: void 1024, c: void 0})) // true
console.log(isEmpty({a: [undefined, undefined]})) // false
console.log(isEmpty({a: 1})) // false
console.log(isEmpty({a: ''})) // false
console.log(isEmpty({a: null, b: undefined})) // falseWe can check with vanilla js with handling null or undefined check also as follows,
function isEmptyObject(obj) {
return !!obj && Object.keys(obj).length === 0 && obj.constructor === Object;
}
//tests
isEmptyObject(new Boolean()); // false
isEmptyObject(new Array()); // false
isEmptyObject(new RegExp()); // false
isEmptyObject(new String()); // false
isEmptyObject(new Number()); // false
isEmptyObject(new Function()); // false
isEmptyObject(new Date()); // false
isEmptyObject(null); // false
isEmptyObject(undefined); // false
isEmptyObject({}); // trueA simpler solution: var a = {};
Case a is empty: !Object.keys(a).length returns true.
Perfect and failsafe solution
I think the first accepted solution works in most cases but is not Failsafe.
The better and failsafe solution will be.
function isEmptyObject() {
return toString.call(obj) === "[object Object]"
&& Object.keys(obj).length === 0;
}
or in ES6/7
const isEmptyObject = () => toString.call(obj) === "[object Object]"
&& Object.keys(obj).length === 0;
With this approach if the obj is set to undefined or null, the code does not break. and return null.
To really accept ONLY {}, the best way to do it in Javascript using Lodash is:
_.isEmpty(value) && _.isPlainObject(value)
My take:
function isEmpty(obj) {
return Object.keys(obj).length === 0;
}
var a = {
a: 1,
b: 2
}
var b = {}
console.log(isEmpty(a)); // false
console.log(isEmpty(b)); // trueJust, I don't think all browsers implement Object.keys() currently.
Meanwhile we can have one function that checks for all 'empties' like null, undefined, '', ' ', {}, [].
var isEmpty = function(data) {
if (typeof(data) === 'object') {
if (JSON.stringify(data) === '{}' || JSON.stringify(data) === '[]') {
return true;
} else if (!data) {
return true;
}
return false;
} else if (typeof(data) === 'string') {
if (!data.trim()) {
return true;
}
return false;
} else if (typeof(data) === 'undefined') {
return true;
} else {
return false;
}
}
//Use cases and results.
console.log(isEmpty()); // true
console.log(isEmpty(null)); // true
console.log(isEmpty('')); // true
console.log(isEmpty(' ')); // true
console.log(isEmpty(undefined)); // true
console.log(isEmpty({})); // true
console.log(isEmpty([])); // true
console.log(isEmpty(0)); // false
console.log(isEmpty('Hey')); // false isEmpty = function(obj) {
if (obj == null) return true;
if (obj.constructor.name == "Array" || obj.constructor.name == "String") return obj.length === 0;
for (var key in obj) if (isEmpty(obj[key])) return true;
return false;
}
This will check the emptiness of String, Array or Object (Maps).
Usage :
var a = {"a":"xxx","b":[1],"c":{"c_a":""}}
isEmpty(a); // true, because a.c.c_a is empty.
isEmpty("I am a String"); //false
Try Destructuring
const a = {};
const { b } = a;
const emptryOrNot = (b) ? 'not Empty' : 'empty';
console.log(emptryOrNot)
function isEmpty(obj) {
for(var i in obj) { return false; }
return true;
}
Under the hood all empty check methods in all libraries use object keys checking logic. Its an odd way to make it understandable, which you can put in a method, Described here.
for(key in obj){
//your work here.
break;
}
Which has evolved in ES5, now put simply you can check the object's keys length, using Object.Keys method which takes your object as it's parameter:
if(Object.keys(obj).length > 0){
//do your work here
}
Or if you are using Lodash (you must be) then.
_.isEmpty(obj) //==true or false
That's similar way of how it gets checked in lodash source for object :
const isEmpty = value => {
for (const key in value) {
if (hasOwnProperty.call(value, key)) {
return false
}
}
return true;
}
But there are many other ways to do that.
Here is a fast, simple, function:
function isEmptyFunction () {
for (const i in this) return false
return true
}
Implemented as a getter:
Object.defineProperty(Object.prototype, 'isEmpty', { get: isEmptyFunction })
console.log({}.isEmpty) // true
Implemented as a separate function:
const isEmpty = Function.prototype.call.bind(isEmptyFunction)
console.log(isEmpty({})) // true
I would go for checking if it has at least one key. That would suffice to tell me that it's not empty.
Boolean(Object.keys(obj || {})[0]) // obj || {} checks for undefined
I liked this one I came up with, with the help of some other answers here. Thought I'd share it.
Object.defineProperty(Object.prototype, 'isEmpty', {
get() {
for(var p in this) {
if (this.hasOwnProperty(p)) {return false}
}
return true;
}
});
let users = {};
let colors = {primary: 'red'};
let sizes = {sm: 100, md: 200, lg: 300};
console.log(
'\nusers =', users,
'\nusers.isEmpty ==> ' + users.isEmpty,
'\n\n-------------\n',
'\ncolors =', colors,
'\ncolors.isEmpty ==> ' + colors.isEmpty,
'\n\n-------------\n',
'\nsizes =', sizes,
'\nsizes.isEmpty ==> ' + sizes.isEmpty,
'\n',
''
);export function isObjectEmpty(obj) {
return (
Object.keys(obj).length === 0 &&
Object.getOwnPropertySymbols(obj).length === 0 &&
obj.constructor === Object
);
}
This include checking for objects containing symbol properties.
Object.keys does not retrieve symbol properties.
Just a workaround. Can your server generate some special property in case of no data?
For example:
var a = {empty:true};Then you can easily check it in your AJAX callback code.
Another way to check it:
if (a.toSource() === "({})") // then 'a' is empty
EDIT: If you use any JSON library (f.e. JSON.js) then you may try JSON.encode() function and test the result against empty value string.
let jsObject = JSON.parse(JSON.stringify(obj), (key, value) => {
if (value === null ||
value === '' ||
(value.constructor === Object && Object.entries(value).length === 0) ||
(value.constructor === Array && value.length === 0)) {
return undefined
}
return value
})
This will filter out all the invalid fields recursively.
As of jQuery 1.4 isEmptyObject() method checks both properties on the object itself and properties inherited from prototypes (in that it doesn't use hasOwnProperty). The argument should always be a plain JavaScript Object as other types of object (DOM elements, primitive strings/numbers, host objects) may not give consistent results across browsers. To determine if an object is a plain JavaScript object, use $.isPlainObject().
jQuery.isPlainObject({}) // true
jQuery.isPlainObject( "test" ) // false
The new Way to check value is if(Object.entries(this.props.myarticle).length===0){ }
here myarticles is object
Sugar.JS provides extended objects for this purpose. The code is clean and simple:
Make an extended object:
a = Object.extended({})
Check it's size:
a.size()
You can use Underscore.js.
_.isEmpty({}); // true
For those of you who have the same problem but use jQuery, you can use jQuery.isEmptyObject.
There is a simple way if you are on a newer browser.
Object.keys(obj).length == 0
2021 - solution
What you need is Object.entries(obj).length. It's not good to touch in native prototype.
You can just create your own function and use it as you want. In my case I have a folder called utils where I have a module definition like this:
utils/isEmpty.js
export default (obj) => !Object.entries(obj).length
someFileToUse.js
import isEmpty from '~/utils/isEmpty.js'
const obj1 = {};
const obj2 = {somekey: "someValue"};
console.log(isEmpty(obj1))
// -> true
console.log(isEmpty(obj2))
// -> false
Caveat! Beware of JSON's limitiations.
javascript:
obj={ f:function(){} };
alert( "Beware!! obj is NOT empty!\n\nobj = { f:function(){} }" +
"\n\nJSON.stringify( obj )\n\nreturns\n\n" +
JSON.stringify( obj ) );
displays
Beware!! obj is NOT empty!
obj = { f:function(){} }
JSON.stringify( obj )
returns
{}
How about using JSON.stringify? It is almost available in all modern browsers.
function isEmptyObject(obj){
return JSON.stringify(obj) === '{}';
}
This one line code helps with fallback to older browsers too.
var a = {}; //if empty returns false
(Object.getOwnPropertyNames ? Object.getOwnPropertyNames(a).length !== 0 : (function(){ for(var key in a) break; return !!key })()) //Returns False
var a = {b:2}; //if not empty returns true
(Object.getOwnPropertyNames ? Object.getOwnPropertyNames(a).length !== 0 : (function(){ for(var key in a) break; return !!key })()) //Returns true
Object.getOwnPropertyNames is implemented in ECMA-5. the above line works in older browsers with a fallback function.
Another quick solution is checking the
lengthproperty ofObject.keys,Object.entriesorObject.values
Knowledge article: Follow this SO post for detailed difference between Object.keys Vs Object.getOwnPropertyNames
I am using this.
function isObjectEmpty(object) {
var isEmpty = true;
for (keys in object) {
isEmpty = false;
break; // exiting since we found that the object is not empty
}
return isEmpty;
}
Eg:
var myObject = {}; // Object is empty
var isEmpty = isObjectEmpty(myObject); // will return true;
// populating the object
myObject = {"name":"John Smith","Address":"Kochi, Kerala"};
// check if the object is empty
isEmpty = isObjectEmpty(myObject); // will return false;
Update
OR
you can use the jQuery implementation of isEmptyObject
function isEmptyObject(obj) {
var name;
for (name in obj) {
return false;
}
return true;
}
You can define you own object prototype, just before its usage or at the beginning of your code.
The definition should look like this:
Object.prototype.hasOwnProperties = function()_x000D_
{ _x000D_
for (var k in this)_x000D_
{ _x000D_
if ( this.hasOwnProperty(k) )_x000D_
{ _x000D_
return true;_x000D_
} _x000D_
}_x000D_
return false;_x000D_
}Here is a usage example:
var a = {};_x000D_
_x000D_
while ( a.status !== "finished" )_x000D_
{ _x000D_
if ( status === "processing" )_x000D_
{_x000D_
a.status = "finished"; _x000D_
}_x000D_
_x000D_
if ( status === "starting" )_x000D_
{_x000D_
a.status = "processing"; _x000D_
}_x000D_
_x000D_
if ( !a.hasOwnProperties() )_x000D_
{_x000D_
a.status = "starting";_x000D_
}_x000D_
}Enjoy! :-)
The following example show how to test if a JavaScript object is empty, if by empty we means has no own properties to it.
The script works on ES6.
const isEmpty = (obj) => {_x000D_
if (obj === null ||_x000D_
obj === undefined ||_x000D_
Array.isArray(obj) ||_x000D_
typeof obj !== 'object'_x000D_
) {_x000D_
return true;_x000D_
}_x000D_
return Object.getOwnPropertyNames(obj).length === 0;_x000D_
};_x000D_
console.clear();_x000D_
console.log('-----');_x000D_
console.log(isEmpty('')); // true_x000D_
console.log(isEmpty(33)); // true_x000D_
console.log(isEmpty([])); // true_x000D_
console.log(isEmpty({})); // true_x000D_
console.log(isEmpty({ length: 0, custom_property: [] })); // false_x000D_
console.log('-----');_x000D_
console.log(isEmpty('Hello')); // true_x000D_
console.log(isEmpty([1, 2, 3])); // true_x000D_
console.log(isEmpty({ test: 1 })); // false_x000D_
console.log(isEmpty({ length: 3, custom_property: [1, 2, 3] })); // false_x000D_
console.log('-----');_x000D_
console.log(isEmpty(new Date())); // true_x000D_
console.log(isEmpty(Infinity)); // true_x000D_
console.log(isEmpty(null)); // true_x000D_
console.log(isEmpty(undefined)); // trueI can't believe after two years of programming js it never clicked that empty objects and array's aren't falsey, the weirdest thing is it never caught me out.
this will return true if the input is falsey by default or if it's an empty object or array. the inverse is the trueish function
http://codepen.io/synthet1c/pen/pjmoWL
function falsish( obj ){
if( (typeof obj === 'number' && obj > 0) || obj === true ){
return false;
}
return !!obj
? !Object.keys( obj ).length
: true;
}
function trueish( obj ){
return !falsish( obj );
}
falsish({}) //=> true
falsish({foo:'bar'}) //=> false
falsish([]) //=> true
falsish(['foo']) //=> false
falsish(false) //=> true
falsish(true) //=> false
// the rest are on codepen
If jQuery and the web browser is not available, there is also an isEmpty function in underscore.js.
_.isEmpty({}) // returns true
Additionally, it does not assume the input parameter to be an object. For a list or string or undefined, it will also turn the correct answer.
if(Object.getOwnPropertyNames(obj).length === 0){
//is empty
}
see http://bencollier.net/2011/04/javascript-is-an-object-empty/
Another alternative is to use is.js (14kB) as opposed to jquery (32kB), lodash (50kB), or underscore (16.4kB). is.js proved to be the fastest library among aforementioned libraries that could be used to determine whether an object is empty.
http://jsperf.com/check-empty-object-using-libraries
Obviously all these libraries are not exactly the same so if you need to easily manipulate the DOM then jquery might still be a good choice or if you need more than just type checking then lodash or underscore might be good. As for is.js, here is the syntax:
var a = {};
is.empty(a); // true
is.empty({"hello": "world"}) // false
Like underscore's and lodash's _.isObject(), this is not exclusively for objects but also applies to arrays and strings.
Under the hood this library is using Object.getOwnPropertyNames which is similar to Object.keys but Object.getOwnPropertyNames is a more thorough since it will return enumerable and non-enumerable properties as described here.
is.empty = function(value) {
if(is.object(value)){
var num = Object.getOwnPropertyNames(value).length;
if(num === 0 || (num === 1 && is.array(value)) || (num === 2 && is.arguments(value))){
return true;
}
return false;
} else {
return value === '';
}
};
If you don't want to bring in a library (which is understandable) and you know that you are only checking objects (not arrays or strings) then the following function should suit your needs.
function isEmptyObject( obj ) {
return Object.getOwnPropertyNames(obj).length === 0;
}
This is only a bit faster than is.js though just because you aren't checking whether it is an object.
I've created a complete function to determine if object is empty.
It uses Object.keys from ECMAScript 5 (ES5) functionality if possible to achieve the best performance (see compatibility table) and fallbacks to the most compatible approach for older engines (browsers).
Solution
/**
* Returns true if specified object has no properties,
* false otherwise.
*
* @param {object} object
* @returns {boolean}
*/
function isObjectEmpty(object)
{
if ('object' !== typeof object) {
throw new Error('Object must be specified.');
}
if (null === object) {
return true;
}
if ('undefined' !== Object.keys) {
// Using ECMAScript 5 feature.
return (0 === Object.keys(object).length);
} else {
// Using legacy compatibility mode.
for (var key in object) {
if (object.hasOwnProperty(key)) {
return false;
}
}
return true;
}
}
Here's the Gist for this code.
And here's the JSFiddle with demonstration and a simple test.
I hope it will help someone. Cheers!
1. Using Object.keys
Object.keys will return an Array, which contains the property names of the object. If the length of the array is 0, then we know that the object is empty.
function isEmpty(obj) {
return Object.keys(obj).length === 0 && empty.constructor === Object;
}
We can also check this using Object.values and Object.entries. This is typically the easiest way to determine if an object is empty.
2. Looping over object properties with for…in
The for…in statement will loop through the enumerable property of object.
function isEmpty(obj) {
for(var prop in obj) {
if(obj.hasOwnProperty(prop))
return false;
}
return true;
}
In the above code, we will loop through object properties and if an object has at least one property, then it will enter the loop and return false. If the object doesn’t have any properties then it will return true.
#3. Using JSON.stringify If we stringify the object and the result is simply an opening and closing bracket, we know the object is empty.
function isEmptyObject(obj){
return JSON.stringify(obj) === '{}';
}
4. Using jQuery
jQuery.isEmptyObject(obj);
5. Using Underscore and Lodash
_.isEmpty(obj);
It's weird that I haven't encountered a solution that compares the object's values as opposed to the existence of any entry (maybe I missed it among the many given solutions).
I would like to cover the case where an object is considered empty if all its values are undefined:
const isObjectEmpty = obj => Object.values(obj).every(val => typeof val === "undefined")
console.log(isObjectEmpty({})) // true
console.log(isObjectEmpty({ foo: undefined, bar: undefined })) // true
console.log(isObjectEmpty({ foo: false, bar: null })) // falseExample usage
Let's say, for the sake of example, you have a function (paintOnCanvas) that destructs values from its argument (x, y and size). If all of them are undefined, they are to be left out of the resulting set of options. If not they are not, all of them are included.
function paintOnCanvas ({ brush, x, y, size }) {
const baseOptions = { brush }
const areaOptions = { x, y, size }
const options = isObjectEmpty(areaOptions) ? baseOptions : { ...baseOptions, areaOptions }
// ...
}
jQuery have special function isEmptyObject() for this case:
jQuery.isEmptyObject({}) // true
jQuery.isEmptyObject({ foo: "bar" }) // false
Read more on http://api.jquery.com/jQuery.isEmptyObject/
This is my preferred solution:
var obj = {};
return Object.keys(obj).length; //returns 0 if empty or an integer > 0 if non-empty
If ECMAScript 5 support is available, you can use Object.keys():
function isEmpty(obj) {
return Object.keys(obj).length === 0;
}
For ES3 and older, there's no easy way to do this. You'll have to loop over the properties explicitly:
function isEmpty(obj) {
for(var prop in obj) {
if(obj.hasOwnProperty(prop))
return false;
}
return true;
}
I was returning an empty JSON response for an AJAX call and in IE8 jQuery.isEmptyObject() was not validating correctly. I added an additional check that seems to catch it properly.
.done(function(data)
{
// Parse json response object
var response = jQuery.parseJSON(data);
// In IE 8 isEmptyObject doesn't catch the empty response, so adding additional undefined check
if(jQuery.isEmptyObject(response) || response.length === 0)
{
//empty
}
else
{
//not empty
}
});
Old question, but just had the issue. Including JQuery is not really a good idea if your only purpose is to check if the object is not empty. Instead, just deep into JQuery's code, and you will get the answer:
function isEmptyObject(obj) {
var name;
for (name in obj) {
if (obj.hasOwnProperty(name)) {
return false;
}
}
return true;
}
Source: Stackoverflow.com