Question

我正在尝试使用JavaScript读取JSON文件的嵌套内容。

这是我的JavaScript：

<script>
var obj, xmlhttp, myObj, x, txt = "";
var request = new XMLHttpRequest();
request.open('GET', 'https://private-c01be-moneyadviceservice.apiary-mock.com/locale/categories.json');
request.setRequestHeader("Content-type", "application/json");
request.onreadystatechange = function () {
if (this.readyState === 4) {
console.log('Status:', this.status);
console.log('Headers:', this.getAllResponseHeaders());
console.log('Body:', this.responseText);

  myObj = JSON.parse(this.responseText);

   for (x in myObj) {
        txt += "<h2>" + myObj[x].title + "</h2><p>" + myObj[x].description + "</p><br/>";
        txt += "<h3>" + myObj[x].contents.title + "</h3><p>" + myObj[x].contents.description + "</p><br/>";
    }

    document.getElementById("MAS").innerHTML = txt; 
  }
};

request.send();
</script>

这是JSON文件：

 {
    "id": "life-events",
    "type": "category",
    "title": "Life events",
    "description": "When big things happen - having a baby, losing your job, getting divorced or retiring\n - it helps to be in control of your money\n",
    "contents": [
        {
            "id": "setting-up-home",
            "type": "category",
            "title": "Setting up home",
            "description": "Deciding whether to rent or buy, working out what you can afford and managing\n money when sharing with others\n",
            "contents": [
            ]
        },
        {
            "id": "young-people-and-money",
            "type": "category",
            "title": "Leaving school or college",
            "description": "",
            "contents": [
            ]
        },
        {
            "id": "having-a-baby",
            "type": "category",
            "title": "Having a baby",
            "description": "",
            "contents": [
            ]
        }
    ]
},

嵌套的JSON显示为“Undefined”。如何访问嵌套数据？

我已经阅读了关于这个主题的无数帖子，但在这个例子中没有一个真正有帮助

Answer 1

你需要遍历contents，因为它们是如下所示的数组：

   for (x in myObj) {
     txt += "<h2>" + myObj[x].title + "</h2><p>" + myObj[x].description + "</p><br/>";
     for(y in myObj[x].contents){
    txt += "<h3>" + myObj[x].contents[y].title + "</h3><p>" + myObj[x].contents[y].description + "</p><br/>";
     }
   }

这是JSBin。

Answer 2

由于myObj[x].contents.title是一个数组，因此您无法访问contents。需要为其{s>属性迭代myObj[x].contents。

使用JavaScript读取嵌套的JSON

2 个答案: