Question

我有3个文件

index.html
data.json
app.js

。我希望遍历JSON数据并更新HTML文件的内容。

这些是我文件的内容：

data.json

{
    "user": [{
        "goal": "HTML essential training",
        "type": "Beginner",
        "date": "20/07/2016"
    }, {
        "goal": "CSS essential training",
        "type": "Beginner",
        "date": "30/07/2016"
    }, {
        "goal": "CSS core concepts",
        "type": "Intermediate",
        "date": "10/08/2016"
    }, {
        "goal": "Javascript essential training",
        "type": "Beginner",
        "date": "20/08/2016"
    }, {
        "goal": "Object Oriented JS",
        "type": "Advanced",
        "date": "30/08/2016"
    }]
}

app.js

var request = new XMLHttpRequest();
request.open('GET', 'data.json');
request.onreadystatechange = function() {
    if ((request.readyState === 4) && (request.status === 200)) {
        var items = JSON.parse(request.responseText);
        console.log(items);

        for (var key in items) {
            console.log(key);
            var output = "<tr><td><input type='checkbox' name='record'></td><td>" + items[key].goal + "</td><td>" + items[key].type + "</td><td>" + items[key].date + "</td></tr>";
            console.log(output);
            $("table tbody").append(output);
            output = '';

        }

    }
}

request.send();

当我运行此代码时，会创建一行，并将所有值设置为undefined。我认为循环逻辑存在问题。请帮助我。

Answer 1

您正在遇到此问题，因为返回的对象是一对key: value。

您需要访问作为数组的user属性。

您的代码

var items=JSON.parse(request.responseText);

解析json字符串后得到的值是key的javascript对象：＆＃39; user＆＃39;和value：这是一个数组

原来是

var data =JSON.parse(request.responseText);
var items = data.user;   <--  this is an array of objects

// iterate using a for loop, since it is not an object technically
for(var i=0; i < items.length; i++) {

Answer 2

看一下你对象的结构：

{
  "user": [
    {
      "goal": "HTML essential training",
      "type": "Beginner",
      "date": "20\/07\/2016"
    },
    {
      "goal": "CSS essential training",
      "type": "Beginner",
      "date": "30\/07\/2016"
    },
    {
      "goal": "CSS core concepts",
      "type": "Intermediate",
      "date": "10\/08\/2016"
    },
    {
      "goal": "Javascript essential training",
      "type": "Beginner",
      "date": "20\/08\/2016"
    },
    {
      "goal": "Object Oriented JS",
      "type": "Advanced",
      "date": "30\/08\/2016"
    }
  ]
}

有一个键，值为数组。

你需要一个这样的循环：

          for (var key in items){if (items.hasOwnProperty(key)) {
              for (var i in items[key]) {if (items[key].hasOwnProperty(i)){
                console.log(items[key][i]);
                var output="<tr><td><input type='checkbox' name='record'></td><td>" + items[key][i].goal + "</td><td>" + items[key][i].type +  "</td><td>" + items[key][i].date + "</td></tr>";
                console.log(output);
                $("table tbody").append(output);
                output='';
              }}
          }}

读取JSON数据并循环遍历它

2 个答案: