跨域进行 JavaScript 调用

Making JavaScript call across domains(跨域进行 JavaScript 调用)

问题描述

这是目标:

移交引用远程服务器上的 JavaScript 文件的脚本标记.该 JavaScript 文件应返回 HTML，然后将显示在调用 HTML 页面上.

Hand off a script tag that references a JavaScript file on a remote server. That JavaScript file should return HTML that will then be displayed on the calling HTML page.

我尝试通过两种方式解决这个问题:

I've attempted to approach this in two ways:

首先，我尝试在 JavaScript 中使用 XMLHttpRequest 来调用这个远程服务器.在 IE 中，它会按预期工作，但 FF、Safari 和 Chrome 会返回一个空响应.我从研究中得到的总体反应是，请求被阻止，因为它尝试访问的服务器与其运行的位置不同(都是本地主机，但端口不同).

First, I attempted to use XMLHttpRequest in JavaScript to call this remote server. In IE, it would work as expected but FF, Safari, and Chrome would return an empty response. The overall response I got from my research was that the request was being blocked since the server it's trying to access is different from where it's running (both localhost, but different ports).

其次，我研究了 Google Gadgets 之类的东西是如何工作的，因为它们有效地为您提供了一个引用外部 JavaScript 的简单脚本标记.据我所知，似乎有某种 iframe 操作仅通过使用的基本 url 进行(下面的示例).这似乎是要走的路，即使使用 iframe 不是我最初的想法.我猜 Google 代码会将 iframe 作为 HTML 返回到嵌入了此脚本的 HTML 文件.

Second, I looked at how things like Google Gadgets work as they effectively give you a simple script tag that's referencing external JavaScript. From what I can gather, it appears that there's some sort of iframe action going on simply by the base url being used (example below). This appears to be the way to go, even though using an iframe wasn't my initial thought. I'm guessing the Google code is returning an iframe as HTML to the HTML file that has this script embedded.

关于我应该如何进行的任何建议?

Any suggestion on how I should proceed?

<script src="http://www.gmodules.com/ig/ifr?url=http://ralph.feedback.googlepages.com/googlecalendarviewer.xml&amp;synd=open&amp;w=320&amp;h=200&amp;title=&amp;border=%23ffffff%7C3px%2C1px+solid+%23999999&amp;output=js"></script>

推荐答案

JSONP是处理同源策略的一种非常常见的方式.由于大多数 javascript 框架(例如 jquery)已经支持它，因此您无需了解技术细节即可使用它.
您也可以通过从 javascript 构造 script 标记(如您所提到的)来自己完成这个技巧.谷歌分析代码片段就是这种方法的一个例子:

JSONP is a very common way to deal with same origin policy. Since most javascript frameworks (e.g., jquery) already support it, you don't have to get into technical details to use it.
You can also do the trick yourself by constructing script tag from javascript (as you mentioned). Google Analytics code snippet is an example of such approach:

      var ga = document.createElement('script');
      ga.type = 'text/javascript';
      ga.async = true;
      ga.src = 'url here';
      var s = document.getElementsByTagName('script')[0];
      s.parentNode.insertBefore(ga, s);

至于 iframe 的想法(如果我理解你的话)，它是行不通的.您可以在页面上使用 iframe 元素来显示来自另一台服务器的内容，但浏览器不允许您使用 javascript 从主页访问它.

As for iframe idea (if I understand you currectly), it's not gonna work. You can use iframe element on your page to display content from another server, but browser won't let you access it from main page using javascript.

编辑
这个原始提案详细介绍了 JSONP 的用法:
http://bob.pythonmac.org/archives/2005/12/05/remote-json-jsonp/

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