如何在加载事件中知道 iframe 内容是 html 还是 json [英] How to know if the iframe content is html or json on load event

问题描述

我有一个绑定到 iframe 的 load 事件的事件处理函数，我想知道 iframe 中检索到的内容是 HTML 还是 JSON.有没有办法做到这一点?

I have an event handler function bound to the load event of an iframe, and I want to know if the content retrieved inside the iframe is HTML or JSON. Is there a way to achieve this?

推荐答案

经过一番研究，我发现最可行的方法是通过 contentType/mimeType 文档 DOM 元素的属性.我们可以通过不同的方式获得这个属性:

After some research, the most feasible way I found to know which kind of content is loaded in the iframe is trough the contentType/mimeType properties of the document DOM element. We can get this property in different ways:

在负载处理函数内部(方式 1):

Inside the load handler function (way 1):

var iframedocument = $(this).contents().get(0);
var contentType = iframedocument.contentType || iframedocument.mimeType;

在负载处理函数内部(方式 2):

Inside the load handler function (way 2):

var iframedocument  = this.contentDocument;
var contentType = iframedocument.contentType || iframedocument.mimeType;

在负载处理函数内部或外部(方式 3):

Inside or outside the load handler function (way 3):

var iframe = document.getElementById('iframe_id');
var iframedocument  = iframe.contentDocument;
var contentType = iframedocument.contentType || iframedocument.mimeType;

如果 contentType == 'application/json' 那么加载的文档是 JSON.如果 contentType == 'text/html' 那么文档是 HTML.

If contentType == 'application/json' then the document loaded is JSON. If contentType == 'text/html' then the document is HTML.

附加说明:这个想法来自 Geoff Wartz 对这个问题的回答:如何使用 jquery 侦听返回的 json 对象 解决方案基于对另一个问题的建议答案:如何从 iframe 获取内容类型?.最后，我们必须使用 contentType 来兼容 Mozilla Firefox，使用 mimeType 来兼容 IE.

Additional notes: The idea came from Geoff Wartz's answer to this question: how to listen for returned json object with jquery The solution was based upon the proposed answer to this other question: How to get content-type from an iframe?. Finally, we have to use contentType for Mozilla Firefox compatibility and mimeType for IE.

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