对象的长度未定义

Question

我有一个对象，我试图获得长度（看看里面有多少个对象）。创建对象的代码如下：

 var threeDSCards = [];
 var card = {}

card[0] = {cardid: 10127, cardnumber: 411111111111, expMonth: 02, expYear: 18};                    
card[1] = {cardid: 10128, cardnumber: 411111111111, expMonth: 01, expYear: 19};

threeDSCards.push(card);

代码在控制台中为对象输出：

[{
"0":{"cardid":10127,"cardnumber":411111111111,"expMonth":2,"expYear":18},
"1":{"cardid":10128,"cardnumber":411111111111,"expMonth":1,"expYear":19}
}]

我期待长度为2，因为对象中存储了2张卡

Answer 1

如果您正在执行上述操作，它将创建一对键值对象，如果您只需要普通对象，则只需创建新变量并将它们推送到数组

<强>样本

＆＃13;

＆＃13;

 var threeDSCards = [];
 var card = {}

var card1 = {cardid: 10127, cardnumber: 411111111111, expMonth: 02, expYear: 18};                    
var card2 = {cardid: 10128, cardnumber: 411111111111, expMonth: 01, expYear: 19};

threeDSCards.push(card1);
threeDSCards.push(card2);
console.log(threeDSCards.length);

＆＃13;

＆＃13;

＆＃13;

Answer 2

您可以使用Object.keys(yourObject).length来获取对象拥有的键（属性）数量。