XMLHttpRequest 无法加载，不存在“Access-Control-Allow-Origin”标头（无法读取 JavaScript/jQuery 中的 Ajax 响应）
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XMLHttpRequest cannot load, No 'Access-Control-Allow-Origin' header is present (Unable to read Ajax response in JavaScript/jQuery )
提问by Venkatesh Achanta
I'm sending an Ajax request to server using jQuery, below is the code snippet.
我正在使用 jQuery 向服务器发送 Ajax 请求，下面是代码片段。
$.ajax({
type: 'POST',
url: "https://store.example.com/account?",
data: "cf=cw&operation=update"
})
Definitely, “requested page” and “Ajax request's URL” are in same domain. Still, Am seeing specified error message in browser console and unable read response with JavaScript/jQuery. Please help me here.
当然，“请求的页面”和“Ajax 请求的 URL”在同一个域中。尽管如此，我还是在浏览器控制台中看到了指定的错误消息，并且无法使用 JavaScript/jQuery 读取响应。请在这里帮助我。
Error message: XMLHttpRequest cannot load https://store.example.com/account?. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://store.example.com' is therefore not allowed access.
错误消息：XMLHttpRequest 无法加载 https://store.example.com/account?。请求的资源上不存在“Access-Control-Allow-Origin”标头。因此不允许访问源“ http://store.example.com”。
采纳答案by Pavan Andhukuri
Are the requesting page and requested URL are in the same domain. Can you try accessing the url using relative path?
请求页面和请求的 URL 是否在同一个域中。您可以尝试使用相对路径访问 url 吗？
$.ajax({
type: 'POST',
url: "/account?",
data: "cf=cw&operation=update"
})
回答by Outlooker
AJAX Requests are only possible if port, protocol and domain of sender and receiver are equal,if not might lead to CORS. CORS stands for Cross-origin resource sharing and has to be supported on the server side.
AJAX 请求只有在发送方和接收方的端口、协议和域相等时才可能，否则可能导致 CORS。CORS 代表跨域资源共享，必须在服务器端支持。
Solution
解决方案
JSONP
JSONP
JSONP or "JSON with padding" is a communication technique used in JavaScript programs running in web browsers to request data from a server in a different domain, something prohibited by typical web browsers because of the same-origin policy.
JSONP 或“带填充的 JSON”是一种通信技术，用于在 Web 浏览器中运行的 JavaScript 程序，以从不同域中的服务器请求数据，由于同源策略，典型的 Web 浏览器禁止这种技术。
Example
例子
$.ajax({
type: 'POST',
url: "https://store.example.com/account?",
dataType: 'jsonp',
success: function (data) {
//code
}
});
Hope this gives you an idea mate.. :)
希望这给你一个想法伙伴.. :)
