我如何获得嵌套数组中特定对象的列表？

Question

如果我运行这个：

var url="https://en.wikipedia.org/w/api.php?format=json&action=query&prop=categories&titles=Victory_Tests&callback=?";
$.getJSON(url,function(data){
    $.each(data, function(i, item) {
        console.log(item);
    });
});

控制台给我：

{pages: {…}}
   pages: 2347232: 
     categories: Array(8)0: 
      {ns: 14, title: "Category:Aftermath of World War II in the United Kingdom"}
      1: {ns: 14, title: "Category:All articles with unsourced statements"}
      2: {ns: 14, title: "Category:Articles with unsourced statements from August 2015"}
      3: {ns: 14, title: "Category:Articles with unsourced statements from March 2009"}
      4: {ns: 14, title: "Category:English cricket seasons from 1919 to 1945"}
      5: {ns: 14, title: "Category:History of Test cricket"}
      6: {ns: 14, title: "Category:Use British English from September 2011"}
      7: {ns: 14, title: "Category:Use dmy dates from September 2011"}
      length: 8
      __proto__: Array(0)
      ns: 0
      pageid: 2347232
      title: "Victory Tests"
    __proto__: 
  Object__proto__: 
 Object__proto__: Object

我需要得到所有 categories

我尝试了 item.categories 和

data.parse.pages.map(function(val){ 
    return val.categories[0]; 
}));

但是不对

Answer 1

假设一页已被return编辑为

Object.values(data.query.pages)[0].categories.map(cat=>cat.title.substr(9))

应该做的工作：

var url="https://en.wikipedia.org/w/api.php?format=json&action=query&prop=categories&titles=Victory_Tests&origin=*";
$.getJSON(url,function(data){
    var pages = Object.values(data.query.pages);
    if(pages.length === 1)
      console.log(pages[0].categories.map(cat => cat.title.substr(9)));
});

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

根据您所需的浏览器支持，您可能需要 Object.values 的 polyfill，例如 https://github.com/tc39/proposal-object-values-entries/blob/master/polyfill.js。

（注意更改后的 URL，在我看来，使用 &origin=* 而不是 &callback=? 是更好的方法，因为它不会 return JSONP 但有效 JSON，也可以通过 XMLHttpRequest/fetch 和 JSON.parse 消耗。）

Answer 2

你应该得到不止一页，如果你想汇总所有内容，请这样做：

 var url="https://en.wikipedia.org/w/api.php?format=json&action=query&prop=categories&titles=Victory_Tests&callback=?";
$.getJSON(url,function(data){
    var categories = Object.values(data.query.pages).map( (i) => i.categories.map( (c) => c.title) );
    console.log(categories);
});

Answer 3

使用API参数formatversion=2:

var url="https://en.wikipedia.org/w/api.php?format=json&formatversion=2&action=query&prop=categories&titles=Victory_Tests&callback=?";
$.getJSON(url,function(data){
    console.log($.map(data.query.pages, function(val){ 
        return val.categories; 
    }));
});

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

（还利用了 jQuery.map 的能力来展平数组。）

我如何获得嵌套数组中特定对象的列表？

How would I get a list of specific objects in an nested array?

javascript

jquery

wikipedia-api