javascript - 如何测试一个空的JavaScript对象？(How do I test for an empty JavaScript object?)

Question

After an AJAX request, sometimes my application may return an empty object, like:

(在AJAX请求之后，有时我的应用程序可能返回一个空对象，例如：)

var a = {};

How can I check whether that's the case?

(如何检查情况呢？)

  ask by falmp translate from so

Answer 1

ECMA 7+ :

(ECMA 7+ ：)

// because Object.entries(new Date()).length === 0;
// we have to do some additional check
Object.entries(obj).length === 0 && obj.constructor === Object

ECMA 5+ :

(ECMA 5+ ：)

// because Object.keys(new Date()).length === 0;
// we have to do some additional check
Object.keys(obj).length === 0 && obj.constructor === Object

Pre-ECMA 5:

(ECMA 5之前的版本：)

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

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

jQuery :

(jQuery的 ：)

jQuery.isEmptyObject({}); // true

lodash :

(lodash ：)

_.isEmpty({}); // true

Underscore :

(下划线 ：)

_.isEmpty({}); // true

Hoek

(ek)

Hoek.deepEqual({}, {}); // true

ExtJS

(ExtJS)

Ext.Object.isEmpty({}); // true

AngularJS (version 1)

(AngularJS（版本1）)

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

Ramda

(拉姆达)

R.isEmpty({}); // true