javascript - check if object is empty

Question

I am trying to create to javascript/jquery test to check if my object is empty and cannot figure it out.

Here is the object when it has something in it:

{"mergedSellerArray":{"key1114":"1120"}}

And here is the object when empty:

{"mergedSellerArray":{}}

This is the current test I have based on another SO answer but it does not work:

var sellers = JSON.stringify({mergedSellerArray});
if(Object.keys(sellers).length === 0 && sellers.constructor === Object) {
    console.log("sellers is empty!");
}

If `sellers` is the outer object, then it *isn't* empty, and you'll have to write some code to check that it matches your expected state. — zzzzBov, Mar 15 '17 at 15:18
`JSON.stringify()` turns the object into a string, as the name suggests. What's the point of the `sellers` variable anyway? Why can't you just check `mergedSellerArray` as is? — JJJ, Mar 15 '17 at 15:20
Remove `JSON.stringify` part and check `mergedSellerArray` object. — dfsq, Mar 15 '17 at 15:22
@JJJ you were right. I should have included the sellers declaration in my original question. I didn't even think about the fact that my sellers was no longer a json object after that stringify command. — dmikester1, Mar 15 '17 at 15:23
check out this similar post https://stackoverflow.com/questions/679915/how-do-i-test-for-an-empty-javascript-object — Solomon Igori, Jun 20 '18 at 15:53

score 48 · Accepted Answer · answered Mar 15 '17 at 15:18

48

You were testing sellers which is not empty because it contains mergedSellerArray. You need to test sellers.mergedSellerArray

let sellers = {
  "mergedSellerArray": {}
};
if (Object.keys(sellers.mergedSellerArray).length === 0 && sellers.mergedSellerArray.constructor === Object) {
  console.log("sellers is empty!");
} else {
  console.log("sellers is not empty !");
}

answered Mar 15 '17 at 15:18

Weedoze

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Downvoted for performance. The entire object is mapped to an array with the use of `Object.keys`, which takes `O(n)` or worse (depending on hash implementation), which imo is pretty irresponsible for a simple "isEmpty" check. An `O(1)` implementation: `let hasNoKeys = obj => { for (let k in obj) return false; return true; }` – Gershom Maes Sep 22 '21 at 05:16

score 4 · Answer 2 · edited Sep 28 '21 at 18:18

4

Here is in jQuery:

$(document).ready(function(){
  var obj={"mergedSellerArray":{}};
  alert("is empty: "+$.isEmptyObject(obj.mergedSellerArray));

  var obj2={"mergedSellerArray":{"key1114":"1120"}};
  alert("is empty: "+$.isEmptyObject(obj2.mergedSellerArray));
})

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js" />

jsfidle: https://jsfiddle.net/nyqgbp38/

edited Sep 28 '21 at 18:18

Super Kai - Kazuya Ito

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answered Mar 15 '17 at 15:26

sharif2008

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The entire jQuery library to test if an object is empty?! – Ohgodwhy May 30 '18 at 02:31
2

It is mentioned that the solution in jquery. thanks – sharif2008 May 31 '18 at 11:05

score 4 · Answer 3 · answered Jan 07 '19 at 17:26

If you are using lodash library, you have an elegant way to check an empty object, array, map or a set. I presume you are aware of ES6 Import statement.

import {isEmpty} from "lodash"

let obj = {};
console.log(isEmpty(obj)); //Outputs true.

let arr = [];
console.log(isEmpty(arr)); //Outputs true.

obj.name="javascript";
console.log(isEmpty(obj)); //Outputs false.

So, for your code,

isEmpty(mergedSellerArray); //will return true if object is not empty.

Hope this answer helped.

score 4 · Answer 4 · answered Feb 17 '21 at 16:21

4

This will work in modern web browser. It is quite easy and simple

const empty = {};
if(Object.keys(empty).length === 0 && empty.constructor === Object) {
    console.log("Object is empty");
} else {
    console.log("Object is not empty");
}

answered Feb 17 '21 at 16:21

Inamur Rahman

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score 2 · Answer 5 · answered Jan 30 '20 at 11:14

Can create the helper function :

const isEmpty = inputObject => {
  return Object.keys(inputObject).length === 0;
};

Can use it like:

let inputObject = {};
console.log(isEmpty(inputObject))  // true.

and

inputObject = {name: "xyz"}; 
console.log(isEmpty(inputObject)) // false

javascript - check if object is empty

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