How to test for an empty object in JavaScript

Today I had the need to check if an object was empty.

Since in JavaScript objects are compared by reference, we can’t do a simple comparison like this:

const obj = {}

if (obj === {}) {
  //no
}

The solution is to pass the object to the built-in method Object.keys() and to check if the object constructor is Object:

const obj = {}

Object.keys(obj).length === 0 && obj.constructor === Object

It’s important to add the second check, to avoid false positives.