Q132: How do you test for an empty object - JavaScript Internals (521 Qs)

There are different solutions based on ECMAScript versions

Using Object entries(ECMA 7+): You can use object entries length along with constructor type.

javascript

  Object.entries(obj).length === 0 && obj.constructor === Object; // Since date object length is 0, you need to check constructor check as well

Using Object keys(ECMA 5+): You can use object keys length along with constructor type.

javascript

  Object.keys(obj).length === 0 && obj.constructor === Object; // Since date object length is 0, you need to check constructor check as well

Using for-in with hasOwnProperty(Pre-ECMA 5): You can use a for-in loop along with hasOwnProperty.

javascript

  function isEmpty(obj) {
    for (var prop in obj) {
      if (obj.hasOwnProperty(prop)) {
        return false;
      }
    }

    return JSON.stringify(obj) === JSON.stringify({});
  }