JavaScript对象中的数组？

Question

我试过看看这是否可行,但我找不到答案.

我正在努力让以下工作:

var defaults = {
 'background-color': '#000',
 color: '#fff',
 weekdays: {['sun','mon','tue','wed','thu','fri','sat']}
};

它只是给出了一个错误,我尝试过使用({...}),[{...}]我希望能够使用以下内容访问工作日:

defaults.weekdays[0];

这可能吗？

Answer 1

杀掉牙箍.

var defaults = {
 backgroundcolor: '#000',
 color: '#fff',
 weekdays: ['sun','mon','tue','wed','thu','fri','sat']
};

Answer 2

// define
var foo = {
  bar: ['foo', 'bar', 'baz']
};

// access
foo.bar[2]; // will give you 'baz'

Answer 3

var data = {
  name: "Ankit",
  age: 24,
  workingDay: ["Mon", "Tue", "Wed", "Thu", "Fri"]
};

for (const key in data) {
  if (data.hasOwnProperty(key)) {
    const element = data[key];
      console.log(key+": ", element);
  }
}

Answer 4

如果你是这样组织的，你可以从一开始就声明整个对象（这个逗号分隔的列表称为对象初始值设定项）：

const myObject = {
    string:     'Galactic Rainbows',
    color:      'HotPink',
    sociopaths: [ "Hitler", "Stalin", "Gates" ]
}

或者，一旦声明了该对象，

  // this line is the declaration:
const myObject = {};  
  // it is equivalent to:
const myObject2 = new Object();

您可以通过给它们值来定义其属性：

myObject.string     = "Galactic Rainbows";
myObject.color      = "HotPink";
myObject.sociopaths = [ "Hitler", "Stalin", "Gates" ];
     //  ^properties  ^values        

下面的所有示例都假设该对象已经声明（如上所述）

我更喜欢像这样单独声明数组，然后将其分配给对象：

const weekdays    = [ 'sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat' ];
myObject.weekdays = weekdays;
myObject.weekdays[0] 
               // => 'sun'

但如果您已经声明了该对象，则编码会更快：

myObject.weekdays = [ 'sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat' ];

但是你不能像这样将数组的数组分配给对象：

myObject.girlsAndBoys[0] = [ "John", "Frank", "Tom"   ];   //Uncaught TypeError: Cannot set property '1' of undefined
myObject.girtsAndBoys[1] = [ "Jill", "Sarah", "Sally" ];   //Uncaught TypeError: Cannot set property '1' of undefined

要将二维数组分配给对象，您有几个选择。您可以先初始化空的二维数组：

myObject.girlsAndBoys    = [[]];
myObject.girlsAndBoys[0] = [ "John", "Frank", "Tom"   ]; 
myObject.girtsAndBoys[1] = [ "Jill", "Sarah", "Sally" ];   

或者你可以一层一层地做：

const boys            = [ "John", "Frank", "Tom"   ];    
const girls           = [ "Jill", "Sarah", "Sally" ];
myObject.girlsAndBoys = [[ boys ],[ girls ]];

或者，您可以一次完成所有操作（不超过对象声明之后）：

const myObject              = {};
myObject.girlsAndBoys       = [[ "John", "Frank", "Tom"   ],
                               [ "Jill", "Sarah", "Sally" ]];
myObject.girlsAndBoys[0][0] == "John";   // returns True