使用带有 JSONP 的 AJAX 未捕获的 SyntaxError 和 CORS 错误

Question

当我执行 AJAX 调用时，出现以下错误：

Uncaught SyntaxError: Unexpected token :

但是，当我直接在浏览器中访问相同的 URL 时，我得到了预期的 JSON 响应。

我做错了什么，我该如何解决？

下面是我的 jQuery AJAX 请求；

$.ajax({
    type: 'GET',
    url: "http://www.exampleUrl.com",
    crossDomain: true,
    dataType: "jsonp",
    jsonp: "jsonp",
    mimeType: "application/json",
    jsonpCallback: 'callback',
    contentType: "application/json; charset=utf-8",
    beforeSend: function() {
        //
    },
    success: function (data) {
        alert("success");
    },
    error: function (result) {
        //      
    }
});

Answer 1

您肯定遇到了 CORS 问题。

这种方法应该很有效：

$.ajax({

  // The 'type' property sets the HTTP method.
  // A value of 'PUT' or 'DELETE' will trigger a preflight request.
  type: 'GET',

  // The URL to make the request to.
  url: 'http://html5rocks-cors.s3-website-us-east-1.amazonaws.com/index.html',

  // The 'contentType' property sets the 'Content-Type' header.
  // The JQuery default for this property is
  // 'application/x-www-form-urlencoded; charset=UTF-8', which does not trigger
  // a preflight. If you set this value to anything other than
  // application/x-www-form-urlencoded, multipart/form-data, or text/plain,
  // you will trigger a preflight request.
  contentType: 'text/plain',

  xhrFields: {
    // The 'xhrFields' property sets additional fields on the XMLHttpRequest.
    // This can be used to set the 'withCredentials' property.
    // Set the value to 'true' if you'd like to pass cookies to the server.
    // If this is enabled, your server must respond with the header
    // 'Access-Control-Allow-Credentials: true'.
    withCredentials: false
  },

  headers: {
    // Set any custom headers here.
    // If you set any non-simple headers, your server must include these
    // headers in the 'Access-Control-Allow-Headers' response header.
  },

  success: function() {
    // Here's where you handle a successful response.
  },

  error: function() {
    // Here's where you handle an error response.
    // Note that if the error was due to a CORS issue,
    // this function will still fire, but there won't be any additional
    // information about the error.
  }
});

来源：Using CORS