如何访问其值为未知整数的JS对象属性? [英] How can I access a JS object property whose value is an unknown integer?

问题描述

此Wikipedia API调用返回的JSON响应是一系列嵌套对象.要遍历对象属性链并访问感兴趣的文本，我首先必须访问一个值为随机数的属性，具体取决于我按标题查询的维基百科页面.

The JSON response returned from this wikipedia API call is a series of nested objects. To travel down the object property chain and access the text of interest, I have to first access a property whose value is a random number, dependent upon the wikipedia page I query by title.

标题为"San%20Francisco"的页面的示例(页面ID = 49728):

An example for the page titled "San%20Francisco" (page id = 49728):

对象属性链:

responseJSON.wiki[0].query.pages[<<page id>>].extract

API调用示例:是否可以通过某种方式识别值是随机整数的属性?链中只有一个页面的子页面，其值为整数.我想不出另一种解决方案，也不知道任何有效的JSON解析方法.

Is there some way that I can identify the property whose value is a random integer? There is only one child of pages in the chain whose value is an integer. I cannot think of another solution and do not know of any JSON parsing method that would be effective.

我对AJAX请求没有经验，并且正在使用jQuery以这种方式进行ajax调用.如果我天真地做些事情，我想提一下:

I am inexperienced with AJAX requests and am making my ajax call in this way using jQuery. I would like to mention this in case I am doing something naive:

var getWiki = function (obj) {
    return $.ajax({
        url: "http://en.wikipedia.org/w/api.php" +
            "?origin=*" + "&format=json" +
            "&action=query" + "&prop=extracts" +
            "&exintro=" + "&explaintext=" + "&titles=" +
            obj.position,
        method: 'GET'
    });
};

推荐答案

如果您的object只有一个键，则可以使用Object.keys(object)[0]获取它，然后对原始object. (这是dig实用程序在下面的示例中所做的.)

If your object has only a single key, you can get it using Object.keys(object)[0] and then perform a dynamic bracket-notation property access on the original object. (This is what the dig utility does in the example below.)

还请注意，您可以使用.promise()来使您的JSON响应处理更加整齐.我建议您也将type: 'json'添加到AJAX请求中，这样就不必自己解析字符串数据.

Also note that you can use .promise() to make handling your JSON response a bit tidier. I would suggest you add type: 'json' to your AJAX request, too, so that you don't have to parse the string data yourself.

function getWiki(obj) {
  return $.ajax({
    url: "http://en.wikipedia.org/w/api.php" +
      "?origin=*" + "&format=json" +
      "&action=query" + "&prop=extracts" +
      "&exintro=" + "&explaintext=" + "&titles=" +
      obj.position,
    method: 'GET',
    type: 'json'
  }).promise()
}


function dig(object) {
  return object[Object.keys(object)[0]]
}


getWiki({
    position: 'San Francisco'
  })
  .then(function(json) {
    console.log(
      dig(json.query.pages).extract //=> 'San Francisco (SF) ...'
    )
  })

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

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