JSON.stringify无法正确转换array.object [英] JSON.stringify not converting array.object correctly

问题描述

我在JSON.stringify上遇到问题

我正在尝试将所有meta标签从页面中拉出，并将它们传递给firefox工作程序文件，以通过它们工作并返回一个对象.

因此，以前没有工作人员运行我的代码时，只有在我转为使用工作程序文件时，我的代码才出现(由于无法进入的原因，我需要使用工作程序！)

所以以前我会使用

来获取所有元标记.

var metas = document.getElementsByTagName("meta");

然后我可以通过使用

遍历metas对象

for (var index in metas){
  var currentMeta = metas[index];
//(and so on, this code worked perfectly)

当我移至外部工作程序文件方案时，会发生问题. 发生了什么事，我照常拉出了meta标签，然后将JSON.stringify应用于可以推送给工作人员的对象.

在介绍完所有内容之后，这就是我的问题的根源: 例如，我在html内带有以下代码的页面上

<meta content="width=1024" name="viewport">
<meta charset="UTF-8">
<meta content="Mozilla Hacks – the Web developer blog" name="title">

如果运行以下代码，我将得到一个数组

var metas = document.getElementsByTagName("meta");

返回3个元素的数组

[meta, meta, meta]

如果我使用:

var jsonMetas = JSON.stringify(metas);

我希望jsonMetas可以保存以下内容:

{"0":{"content":"width=1024","name":"viewport"},"1":{"charset":"UTF-8"},"2":{"content":"Mozilla Hacks - the web developer blog","name":"title"} }

但是，当我查看jsonMetas对象时，我看到此返回:

{"0":{"constructor":{}},"1":{"constructor":{}},"2":{"constructor":{}}}

呵呵?????

我不太擅长JavaScript，所以请您解释一下(很简单):)发生了什么事?

为什么stringify调用返回异常结构化的对象? 我在做什么错了?

预先感谢您的回答.

解决方案

您可以使用以下:

var metas = document.getElementsByTagName("meta");
var arr = [];
for (var i = 0; i < metas.length; i++) {
    var obj = {};
    for (var j = 0; j < metas[i].attributes.length; j++) {
        var att = metas[i].attributes[j];
        obj[att.name] = att.value;
    }
    arr.push(obj);
}

var jsonMetas = JSON.stringify(arr);
console.log(jsonMetas);​

导致:

[
    {
        "http-equiv": "content-type",
        "content": "text/html; charset=UTF-8"
    },
    {
        "content": "width=1024",
        "name": "viewport"
    },
    {
        "charset": "UTF-8"
    },
    {
        "content": "Mozilla Hacks – the Web developer blog",
        "name": "title"
    }
]

I'm having a problem with JSON.stringify

I'm trying to pull all the meta tags out of the page and pass them to a firefox worker file to work through them and to return back an object.

So my code previously worked when I didn't have a worker running the issue has only cropped up when I have moved to using worker file (for reasons I can't go into I need to use a worker!)

So previously I would get all the meta tags using

var metas = document.getElementsByTagName("meta");

then I could loop through the metas object by using

for (var index in metas){
  var currentMeta = metas[index];
//(and so on, this code worked perfectly)

The problem occurs when I move to the external worker file scenario. What happens is I pull the meta tags out as normal, and then I use JSON.stringify to something that I can push to the worker.

After all that intro blab, here is the root of my problem: Take for example that I land on a page with the following code within the html

<meta content="width=1024" name="viewport">
<meta charset="UTF-8">
<meta content="Mozilla Hacks – the Web developer blog" name="title">

If I run the following code I get an array

var metas = document.getElementsByTagName("meta");

returns an array 3 elements

[meta, meta, meta]

If I stringify it using:

var jsonMetas = JSON.stringify(metas);

I would expect to jsonMetas to hold something like:

{"0":{"content":"width=1024","name":"viewport"},"1":{"charset":"UTF-8"},"2":{"content":"Mozilla Hacks - the web developer blog","name":"title"} }

However when I look at the jsonMetas object I see this returned:

{"0":{"constructor":{}},"1":{"constructor":{}},"2":{"constructor":{}}}

Huh?????

I'm not that good at JavaScript, so could you please explaining (in very small words :) ) what is going on?

Why does the stringify call return the unusually structured object? What am I doing wrong?

Thanks in advance for your answers.

解决方案

You could use the following:

var metas = document.getElementsByTagName("meta");
var arr = [];
for (var i = 0; i < metas.length; i++) {
    var obj = {};
    for (var j = 0; j < metas[i].attributes.length; j++) {
        var att = metas[i].attributes[j];
        obj[att.name] = att.value;
    }
    arr.push(obj);
}

var jsonMetas = JSON.stringify(arr);
console.log(jsonMetas);​

results in:

[
    {
        "http-equiv": "content-type",
        "content": "text/html; charset=UTF-8"
    },
    {
        "content": "width=1024",
        "name": "viewport"
    },
    {
        "charset": "UTF-8"
    },
    {
        "content": "Mozilla Hacks – the Web developer blog",
        "name": "title"
    }
]

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