javascript XMLHttpRequest 无法加载 URL。Access-Control-Allow-Origin 不允许的来源
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XMLHttpRequest cannot load URL. Origin not allowed by Access-Control-Allow-Origin
提问by Scott Newson
I want to make a small website that uses xml data from another domain. (Weather data from Weather Underground: www.wunderground.com). I am using just html and javascript, and writing it all in Visual Studio Express 2012 for Web.
我想制作一个使用来自另一个域的 xml 数据的小型网站。（来自 Weather Underground 的天气数据：www.wunderground.com）。我只使用 html 和 javascript，并在 Visual Studio Express 2012 for Web 中全部编写。
I make and send the xml request as follows:
我按如下方式发出并发送 xml 请求：
url = "http://api.wunderground.com/api/3c6e3d838e217361/geolookup/conditions/forecast/q/51.11999893,-114.01999664.xml";
xmlhttp = new XMLHttpRequest();
xmlhttp.open("GET", url, false);
xmlhttp.send();
xmlDoc = xmlhttp.responseXML;
The problem is that I get the following error in the Google Chrome (version 29.0.1547.66) developer console:
问题是我在 Google Chrome（版本 29.0.1547.66）开发人员控制台中收到以下错误：
XMLHttpRequest cannot load http://api.wunderground.com/api/3c6e3d838e217361/geolookup/conditions/forecast/q/51.11999893,-114.01999664.xml. Origin http://localhost:49933 is not allowed by Access-Control-Allow-Origin.
Or this on Internet Explorer (version 10.0.8) console:
或者在 Internet Explorer（版本 10.0.8）控制台上：
SEC7118: XMLHttpRequest for http://api.wunderground.com/api/3c6e3d838e217361/geolookup/conditions/forecast/q/51.11999893,-114.01999664.xml required Cross Origin Resource Sharing (CORS).
As I understand it, CORS (http://enable-cors.org/) needs effort by both the client and the server to work. I want to assume that the Weather Underground API knows what it is doing and has enabled things appropriately, such as setting the response header to include 'Access-Control-Allow-Origin: *', and I know that I get the same problems when I try the same code using another API provider (World Weather Online). So I think this is something I should be able to fix in my client code. Another SO answer where the suggestion is to fix the server-side header: CORS with XMLHttpRequest
据我了解，CORS（http://enable-cors.org/）需要客户端和服务器共同努力才能工作。我想假设 Weather Underground API 知道它在做什么并适当地启用了一些东西，例如将响应头设置为包含“Access-Control-Allow-Origin: *”，并且我知道当我遇到相同的问题时我使用另一个 API 提供程序（World Weather Online）尝试相同的代码。所以我认为这是我应该能够在我的客户端代码中修复的东西。另一个建议是修复服务器端标头的 SO 答案： CORS with XMLHttpRequest
I have tried to find answers, but don't understand articles such as: http://dev.opera.com/articles/view/dom-access-control-using-cross-origin-resource-sharing/http://saltybeagle.com/2009/09/cross-origin-resource-sharing-demo/
我试图找到答案，但不明白诸如： http: //dev.opera.com/articles/view/dom-access-control-using-cross-origin-resource-sharing/ http:// saltybeagle.com/2009/09/cross-origin-resource-sharing-demo/
采纳答案by Prasath K
Use Ajaxwith JSONP if you want in jquery
如果你想在 jquery 中使用Ajax和 JSONP
For javascript see here , http://developer.chrome.com/extensions/xhr.htmland http://www.leggetter.co.uk/2010/03/12/making-cross-domain-javascript-requests-using-xmlhttprequest-or-xdomainrequest.html
对于 javascript，请参见此处，http://developer.chrome.com/extensions/xhr.html和http://www.leggetter.co.uk/2010/03/12/making-cross-domain-javascript-requests-using -xmlhttprequest-或-xdomainrequest.html
Use .jsonformat data rather than .xmlto make your application simpler and faster i.e http://api.wunderground.com/api/3c6e3d838e217361/geolookup/conditions/forecast/q/51.11999893,-114.01999664.json
使用.json格式数据而不是.xml使您的应用程序更简单、更快，即http://api.wunderground.com/api/3c6e3d838e217361/geolookup/conditions/forecast/q/51.11999893,-114.01999664.json
