js调用问题
最近用js调用另一个站点时报错了，报错信息：No ‘Access-Control-Allow-Origin‘ header is present on the requested resource。js跨域问题。
后台C#接口
使用默认的回调函数：
???public class DemoController : ApiController ???{ ???????[Route("~/demo")] ???????[HttpGet] ???????public HttpResponseMessage Demo(int OrderId) //C#传参数不区分大小写 ???????{ ???????????HttpResponseMessage response = Request.CreateResponse(); ???????????response.StatusCode = HttpStatusCode.OK; ???????????response.Content = new StringContent(String.Format("callbackFun({0})", (new { IsSuccess = "-1000", Msg = "resp.Msg" }).ToJson())); ???????????return response; ???????} ???}前台js调用示例：(回调函数和后台指定一致，可以不申明function callbackFun(data)函数，默认success函数会被调用；如果申明了callbackFun函数，会先调callbackFun，然后再调success函数)
<head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>jquery</title><script src="https://code.jquery.com/jquery-3.1.1.min.js"></script><script type="text/javascript">function b_click(){ ???$.ajax({ ???????type:"GET", ???????async:false, ???????dataType: ‘jsonp‘, //跨域调用 ??? jsonpCallback: "callbackFun", ?//指定回调函数名称 ???????data: {"orderId":4811}, ???????//timeout: 5000, //超时设置 ???????//contentType: "application/json;utf-8", ???????url:"http://ab.test.com/demo", ???????success:function(result){ ???????????console.log("success"); ???????????console.log(result); ???????????alert(result.Msg); ???????}, ???????error:function(result){ ???????????console.log("fail"); ???????????console.log(result); ???????????alert(result.Msg); ???????} ???}); ???????//function callbackFun(data){ ???????//console.log("call"); ???//}}</script></head><body data-spy="scroll" data-target=".navbar-example"> <input type="button" value="click me!" onclick="b_click();" /></body></html>浏览器看js请求链接：http://ab.test.com/demo?callback=callbackFun&orderId=4811
可以看出：如果不指定回调参数名称，默认是callback
指定回调函数名：
服务端接口：
???public class DemoController : ApiController ???{ ???????[Route("~/demo")] ???????[HttpGet] ???????public HttpResponseMessage DemoCheck(int OrderId, String callbackMethod) ???????{ ???????????HttpResponseMessage response = Request.CreateResponse(); ???????????response.StatusCode = HttpStatusCode.OK; ???????????response.Content = new StringContent(String.Format(callbackMethod + "({0})", (new { IsSuccess = "-1000", Msg = "resp.Msg" }).ToJson())); ???????????return response; ???????} ???}接口返回结果：
指定回调参数名和值：
<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>jquery</title><script src="https://code.jquery.com/jquery-3.1.1.min.js"></script><script type="text/javascript">function b_click(){ ???$.ajax({ ???????type:"POST", ???????async:false, ???????dataType: ‘jsonp‘,
//jsonp的值自定义,如果使用callbackMethod,那么服务器端,要返回一个callbackMethod的值对应的对象. ???????jsonp: ‘callbackMethod‘, ???????jsonpCallback: "callbackFun", ?//指定回调函数名称 ???????data: {"orderId":4811}, ???????//timeout: 5000, ???????//contentType: "application/json;utf-8", ???????url:"http://ab.test.com/demo", ???????success:function(result){ ???????????console.log("success"); ???????????console.log(result); ???????????alert(result.Msg); ???????}, ???????error:function(result){ ???????????console.log("fail"); ???????????console.log(result); ???????????alert(result.Msg); ???????} ???});}</script></head><body data-spy="scroll" data-target=".navbar-example"> <input type="button" value="click me!" onclick="b_click();" /></body></html>请求url：http://ab.test.com/demo?callbackMethod=callbackFun&orderId=4811
jsonp跨域
原文地址：http://www.cnblogs.com/mr-yang-localhost/p/7684653.html