How Can I Effectively Determine if a JavaScript Object is Empty?

Determining the Emptiness of JavaScript Objects

To ascertain whether a JavaScript object is empty, various methods and considerations are available. One approach involves utilizing a for...in loop in conjunction with Object.hasOwn (ECMA 2022 ). This loop iterates through an object's own properties and returns false if any exist:

function isEmpty(obj) {
  for (const prop in obj) {
    if (Object.hasOwn(obj, prop)) {
      return false;
    }
  }

  return true;
}

Another method distinguishes tussen empty objects and other objects lacking own properties. This can be achieved through type checks:

function isEmptyObject(value) {
  if (value == null) {
    return false;
  }

  if (typeof value !== 'object') {
    return false;
  }

  const proto = Object.getPrototypeOf(value);

  if (proto !== null && proto !== Object.prototype) {
    return false;
  }

  return isEmpty(value);
}

It's crucial to note that comparing against Object.prototype may overlook cross-realm objects. Additionally, Object.keys(obj).length is discouraged as it's inefficient, requiring the creation of an array.

For compatibility with older JavaScript engines, Object.hasOwn can be replaced with Object.prototype.hasOwnProperty.call:

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

  return true;
}

Various libraries offer functions specifically designed to check for empty objects:

• jQuery: jQuery.isEmptyObject({}) // true
• Lodash: _.isEmpty({}) // true
• Underscore: _.isEmpty({}) // true
• Hoek: Hoek.deepEqual({}, {}) // true
• ExtJS: Ext.Object.isEmpty({}) // true
• AngularJS (version 1): angular.equals({}, {}) // true
• Ramda: R.isEmpty({}) // true

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