Question

我想为名为gender的值添加一个新属性，默认值为＆＃34; male＆＃34;。完成添加属性的唯一方法是通过数组循环。或者是否有更有效的策略？

var data = [];
data.push({id: 1, values: {"age":33,"name":"Duke"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
var obj;
for obj in data {
  obj.values.gender = "male";
}

所以data将是

data = [
   {id: 1, values: {"age":33,"name":"Duke","gender":"male"}},
   {id: 1, values: {"age":34,"name":"Dave","gender":"male"}}
];

Answer 1

我害怕说你无法避免for循环。但是，我已经为您创建了一个比较，您可以考虑性能。正如预期的那样，简单的for循环总是更快。看看：

＆＃13;

var data = [];

data.push({id: 1, values: {"age":33,"name":"Duke"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});
data.push({id: 2, values: {"age":34,"name":"Dave"}});

function foreachFn(d){
 d.forEach(function(el){ el.values.gender='male'; });
  return d;
}


function simpleLoopFn(d){
  for (var i = 0;i<d.length;i++){
    d[i].values.gender = "male";
 }
}

function mappingData(d){
  let newdata = d.map(function(el)
  {
     el.values.gender = 'male';
  });
}


var t1 = 0, t2 =0;
let foreachData=data;
t1 = console.time('foreachFn')
foreachFn(foreachData);
t2 = console.timeEnd('foreachFn');

let simpleData= data;
t1 = console.time('simpleLoopFn')
simpleLoopFn(simpleData);
t2 = console.timeEnd('simpleLoopFn');

let mappedData = data;
t1 = console.time('mappingData')
mappingData(mappedData);
t2 = console.timeEnd('mappingData');

＆＃13;

Answer 2

您可以尝试使用OOP Javascript并使用原型向该类型的所有对象添加属性：

function Person(age, name) {
    this.age = age;
    this.name = name;
}

var data = [];
data.push({id: 1, values: new Person(33, "Duke") });
data.push({id: 2, values: new Person(34, "Dave") });

Person.prototype.gender = 'male';

console.log(data[0].values.gender) // male

如果您知道要添加的属性并且它不是动态的，那么@ Tom的答案会更好。如果要分配给所有对象的属性在运行时之前是未知的，那么我的解决方案会更好。

Answer 3

有。您可以使用对象和构造函数为属性分配默认值。代码说的不仅仅是文字：

var Person = (function () {
    function Person(age, name, gender) {
        this.age = age;
        this.name = name;
        this.gender = gender ? gender : "male";
    }

    return Person;
}());

var data = [];
data.push({ id: 1, values: new Person(33, "Duke") });
data.push({ id: 2, values: new Person(34, "Dave") });

变为：

data = [
    {
        id: 1,
        values: {
            "age": 33,
            "name": "Duke",
            "gender":"male"
        }
    },
    {
        id: 2,
        values: {
            "age": 34,
            "name": "Dave",
            "gender":"male"
        }
    }
]

您甚至可以执行以下操作来更改男性以外的性别：

data.push({ id: 2, values: new Person(35, "Jessica", "female") });

的jsfiddle： https://jsfiddle.net/wtomcskr/1/

将具有默认值的新属性添加到javascript对象数组中

3 个答案: