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sirdaiz
Asked: 2020-09-17 01:53:31 +0800 CST 2020-09-17 01:53:31 +0800 CST

如何检查空对象？- JavaScript

  • 772

我有以下代码：

var obj = {};

if (obj != null) {
    //execute
}

问题是obj它不为空。

我如何知道一个对象是否为空以便它进入一个条件？

javascript

4 Answers

  1. Best Answer

    与ES5：Object.keys()

    let obj = {};

console.log( Object.keys(obj).length === 0 )

    与jQuery：jQuery.isEmptyObject()

    let obj = {};

console.log( $.isEmptyObject(obj) );
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

    • 26

  2. @aldanux 的答案是正确的，但一种选择是将其设为字符串JSON.stringify(obj) 

    var obj = {};

if (JSON.stringify(obj)=='{}') {
    //execute
    console.log('vacio');
}

    我们也可以使用Object.entries(obj).

    var obj = {};

if (Object.entries(obj).length === 0) {
  //execute
  console.log('vacio');
}

    • 8

  3. 我建议使用 Lodash。 https://lodash.com/docs/4.17.15#isEmpty

    _.isEmpty(null);
// => true
 
_.isEmpty(true);
// => true
 
_.isEmpty(1);
// => true
 
_.isEmpty([1, 2, 3]);
// => false
 
_.isEmpty({ 'a': 1 });
// => false
    • 0 

  4. function objetoVacio(obj) {
  for (var prop in obj) {
    if (obj.hasOwnProperty(prop)) return false;
  }
  return true;
}
console.log(objetoVacio({}));
console.log(objetoVacio({hola: 'mundo'}));

    function objetoVacio(obj) {
    return Object.getOwnPropertyNames(obj).length === 0;
}
console.log(objetoVacio({}));
console.log(objetoVacio({hola: 'mundo'}));

    • 0