javascript - check if object is empty [duplicate]

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!");
}

Answer 1

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 !");
}

Answer 2

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.

Answer 3

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");
}

Answer 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/

Answer 5

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