How to Test for Empty JavaScript Object

JavaScript object is a powerful data structure that allows you to easily store different data types in a compact manner. It is advisable to check if JS object is empty before you use it. Otherwise, your JS code may throw an error and stop code execution. In this article, we will learn how to test for empty JavaScript object in different JavaScript languages and libraries.

How to Test for Empty JavaScript Object

Let us say you have the following JS object.

obj

Here is the plain JavaScript code to check if it is empty or not.

obj // null and undefined check
&& Object.keys(obj).length === 0
&& Object.getPrototypeOf(obj) === Object.prototype

The above code consists of 3 checks. The first one checks if the object is null/undefined. The second check tests if it has no keys (empty). The third one checks if it is actually an object data type or some other data.

If the result of above expression is true then the JS object is empty, else it is not.

If you use jQuery, then you can easily check if a JS object is empty or not using isEmptyObject() function. It returns true if the passed object is empty, else it returns false.

jQuery.isEmptyObject(obj); // true

If you use popular JS libraries like Lodash or Underscore, you can isEmpty() function to check if an object it empty or not.

_.isEmpty(obj); // true

If you use ExtJS library, you can use its isEmpty() function as shown below.

Ext.Object.isEmpty(obj); // true

With AngularJS you need to compare the JS object with an empty object to check if it is empty or not.

angular.equals(obj, {}); // true

In this article, we have learnt how to easily check if a JS object is empty or not, using plain JavaScript as well as various JS libraries.

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