访问嵌套属性 json

Question

我有这个 json：

{"objects":[{"text":{"x":643,"y":71,"width":82,"height":33,"font":"Arial","style":"bold","size":24,"label":"Part A"}},
{"text":{"x":643,"y":116,"width":389,"height":42,"font":"Arial","style":"bold","size":16,"label":"What does \"novel\" mean as it is used in paragraph 8 of \"Turning Down a New Road\"? "}},
{"radiobutton":{"x":643,"y":170,"width":100,"height":20,"label":"A. old"}},{"radiobutton":{"x":643,"y":209,"width":100,"height":20,"label":"B. afraid"}},
{"radiobutton":{"x":643,"y":250,"width":100,"height":20,"label":"C. new"}},
{"radiobutton":{"x":643,"y":289,"width":100,"height":20,"label":"D. friendly"}}]}

我需要获取每个元素的属性，但是我无法获取第二级的属性，我的意思是我无法知道该元素是否为“文本”、“单选按钮”、“标签”，我三级属性没问题。

这是我的来源：

                   $.ajax({
                        url: 'generateobject.php',
                        dataType: 'json',
                        type: 'GET'
                    }).done(function(data) {
                        $.each(data, function(index, firstLevel) {
                            $.each(firstLevel, function(anotherindex, secondLevel) {
                                alert(secondLevel[0]);//shows [object Object]
                                $.each(secondLevel, function(yetAnotherIndex, thirdLevel) {
                                    //alert(thirdLevel.y+''+thirdLevel.y);
                                });
                            });
                        });
                    });

二级属性如何获取？

Answer 1

使用Object.keys(data) 并访问第一项。如果您运行 sn-p，您应该会看到预期的类型警报：

var data = {"objects":[{"text":{"x":643,"y":71,"width":82,"height":33,"font":"Arial","style":"bold","size":24,"label":"Part A"}},
{"text":{"x":643,"y":116,"width":389,"height":42,"font":"Arial","style":"bold","size":16,"label":"What does \"novel\" mean as it is used in paragraph 8 of \"Turning Down a New Road\"? "}},
{"radiobutton":{"x":643,"y":170,"width":100,"height":20,"label":"A. old"}},{"radiobutton":{"x":643,"y":209,"width":100,"height":20,"label":"B. afraid"}},
{"radiobutton":{"x":643,"y":250,"width":100,"height":20,"label":"C. new"}},
{"radiobutton":{"x":643,"y":289,"width":100,"height":20,"label":"D. friendly"}}]};


$.each(data, function(index, firstLevel) {
  $.each(firstLevel, function(anotherindex, secondLevel) {
    alert(Object.keys(secondLevel)[0]);
    $.each(secondLevel, function(yetAnotherIndex, thirdLevel) {
      //alert(thirdLevel.y+''+thirdLevel.y);
    });
  });
});

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