Question

示例：

var myArray = ['e', {pluribus: 'unum'}];

如何获得第一个＆＃39;？

我的实际数组如下所示：

({'U.S., MCC':{score:"88.88", url:"http://ati.publishwhatyoufund.org/donor/usmcc/"}, GAVI:{score:"87.26", url:"http://ati.publishwhatyoufund.org/donor/gavi/"}, 'UK, DFID':{score:"83.49", url:"http://ati.publishwhatyoufund.org/donor/ukdfid/"}, UNDP:{score:"83.38", url:"http://ati.publishwhatyoufund.org/donor/undp/"}, 'World Bank, IDA':{score:"73.81", url:"http://ati.publishwhatyoufund.org/donor/world-bank-ida/"}, 'Global Fund':{score:"70.65", url:"http://ati.publishwhatyoufund.org/donor/global-fund/"}})

我需要得到这个名字。即美国，MCC＆＃39;然后得分和网址 - 我在高图中使用它作为图表中的数据点。

我知道它应该很简单，但我是一个完整的JS noob。

由于

Answer 1

要从数组中获取第一个元素，只需使用：

myArray[0]

请注意0指向数组中的第一个元素。数组是零索引的。

请查看this mdn page about arrays了解详情。

然而，你所拥有的不是数组，它是一个对象。您无法使用数字键（如0, 1, 2等）

访问这些内容

要获取对象的第一个元素，必须使用＆＃34;键＆＃34;获得该价值假设：

var myObject = {'U.S., MCC':{score:"88.88", url:"http://ati.publishwhatyoufund.org/donor/usmcc/"}, GAVI:{score:"87.26", url:"http://ati.publishwhatyoufund.org/donor/gavi/"}, 'UK, DFID':{score:"83.49", url:"http://ati.publishwhatyoufund.org/donor/ukdfid/"}, UNDP:{score:"83.38", url:"http://ati.publishwhatyoufund.org/donor/undp/"}, 'World Bank, IDA':{score:"73.81", url:"http://ati.publishwhatyoufund.org/donor/world-bank-ida/"}, 'Global Fund':{score:"70.65", url:"http://ati.publishwhatyoufund.org/donor/global-fund/"}}

然后：

myObject['U.S., MCC']

将是：

{score:"88.88", url:"http://ati.publishwhatyoufund.org/donor/usmcc/"}

或者，作为一个更简单的例子：

var foo = {
    'bar': 1,
    'wut': {'nested': 'you can nest objects! (and arrays, etc)'}
    baz: 'Objects, woo!',  // Quotes around keys aren't mandatory, unless you have
}                          // spaces in the keys: 'quotes mandatory'

foo['bar']     // 1
foo.wut.nested // 'you can nest objects! (and arrays, etc)'
foo.baz        // 'Objects, woo!' (you don't have to use the square brackets,
               //                  if the key is a simple string (No spaces))

请查看this mdn article about working with objects以了解有关这些内容的更多信息。

现在，要真正得到第一个＆＃34;该对象中的元素很棘手，因为对象没有排序。（即使它们看起来如此。）

您可以使用for...in循环浏览对象，但不保证这些项目会在不同的浏览器上以相同的顺序显示：

for (var key in myObject) {
    if (myObject.hasOwnProperty(key)) { // Make sure it's a proper element on the object, not a prototype function.
        // key == ''U.S., MCC', for example,
        doSomethingWith(myObject[key]);
    }
}

您可以按排序顺序迭代对象，但有一些better answers out there。

Answer 2

尝试使用这种情况：

var myObj = {'U.S., MCC':{score:"88.88", url:"http://ati.publishwhatyoufund.org/donor/usmcc/"}, GAVI:{score:"87.26", url:"http://ati.publishwhatyoufund.org/donor/gavi/"}, 'UK, DFID':{score:"83.49", url:"http://ati.publishwhatyoufund.org/donor/ukdfid/"}, UNDP:{score:"83.38", url:"http://ati.publishwhatyoufund.org/donor/undp/"}, 'World Bank, IDA':{score:"73.81", url:"http://ati.publishwhatyoufund.org/donor/world-bank-ida/"}, 'Global Fund':{score:"70.65", url:"http://ati.publishwhatyoufund.org/donor/global-fund/"}};

for(v in myObj) {
    console.log("Obj key: "+v, myObj[v]);
}

Javascript - 如何获取数组中的第一个元素？

2 个答案: