迭代json对象javascript

Question

我正在努力寻找一种以我喜欢的方式迭代这个JSON对象的方法.我在这里只使用Javascript.

首先,这是对象

{
"dialog":
{
    "dialog_trunk_1":{
        "message": "This is just a JSON Test"
    },

    "dialog_trunk_2":{
        "message": "and a test of the second message"
    },

    "dialog_trunk_3":
    {
        "message": "This is a test of a bit longer text. Hopefully this will at the very least create 3 lines and trigger us to go on to another box. So we can test multi-box functionality, too."
    }
}
}

现在,我只是尝试基本方法来访问此对象上的每个dialog_trunk.理想情况下,我想循环遍历对象和每个主干,显示它的message值.

我已经尝试使用for循环来动态生成dialog_trunk的名称/编号,但我无法使用对象名称的字符串访问该对象,因此我不确定从何处开始.

Answer 1

你使用一个for..in循环.请务必检查对象是否拥有属性,还是显示所有继承的属性.一个例子是这样的:

var obj = {a: 1, b: 2};
for (var key in obj) {
  if (obj.hasOwnProperty(key)) {
    var val = obj[key];
    console.log(val);
  }
}

或者,如果您需要递归来遍历所有属性:

var obj = {a: 1, b: 2, c: {a: 1, b: 2}};
function walk(obj) {
  for (var key in obj) {
    if (obj.hasOwnProperty(key)) {
      var val = obj[key];
      console.log(val);
      walk(val);
    }
  }
}
walk(obj);

Answer 2

我的问题实际上是使用JSON对象而不是实际逻辑问题进行错误规划的问题.根据user2736012的建议,我最终要做的是如下组织对象.

{
"dialog":
{
    "trunks":[
    {
        "trunk_id" : "1",
        "message": "This is just a JSON Test"
    },
    {
        "trunk_id" : "2",
        "message": "This is a test of a bit longer text. Hopefully this will at the very least create 3 lines and trigger us to go on to another box. So we can test multi-box functionality, too."
    }
    ]
}
}

那时,我能够根据对象的总数做一个相当简单的for循环.

var totalMessages = Object.keys(messages.dialog.trunks).length;

    for ( var i = 0; i < totalMessages; i++)
    {
        console.log("ID: " + messages.dialog.trunks[i].trunk_id + " Message " + messages.dialog.trunks[i].message);
    }

但是,我的所有浏览器都不支持获取totalMessages的方法.对于我的项目,它实际上并不重要,但要小心,如果你选择使用类似的东西.

Answer 3

这是我的递归方法:

function visit(object) {
    if (isIterable(object)) {
        forEachIn(object, function (accessor, child) {
            visit(child);
        });
    }
    else {
        var value = object;
        console.log(value);
    }
}

function forEachIn(iterable, functionRef) {
    for (var accessor in iterable) {
        functionRef(accessor, iterable[accessor]);
    }
}

function isIterable(element) {
    return isArray(element) || isObject(element);
}

function isArray(element) {
    return element.constructor == Array;
}

function isObject(element) {
    return element.constructor == Object;
}