<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.js" type="text/javascript"></script>
<script>
$.get("http://example.com/", function(data) {
alert(data);
});
</script>
它对那个URL做一个OPTIONS请求，然后回调永远不会被调用任何东西。
当它不是跨域时，它工作得很好。
jQuery不应该只是调用一个<script>节点，然后在它加载时做回调吗?我知道我将无法得到的结果(因为它是跨域)，但这是可以的;我只想让电话接通。这是bug，还是我做错了什么?
当前回答
根据MDN，
Preflighted requests Unlike simple requests (discussed above), "preflighted" requests first send an HTTP OPTIONS request header to the resource on the other domain, in order to determine whether the actual request is safe to send. Cross-site requests are preflighted like this since they may have implications to user data. In particular, a request is preflighted if: It uses methods other than GET or POST. Also, if POST is used to send request data with a Content-Type other than application/x-www-form-urlencoded, multipart/form-data, or text/plain, e.g. if the POST request sends an XML payload to the server using application/xml or text/xml, then the request is preflighted. It sets custom headers in the request (e.g. the request uses a header such as X-PINGOTHER)
其他回答
看起来Firefox和Opera(在mac上也测试过)不喜欢这种交叉域(但Safari没问题)。
您可能必须调用本地服务器端代码来压缩远程页面。
根据MDN，
Preflighted requests Unlike simple requests (discussed above), "preflighted" requests first send an HTTP OPTIONS request header to the resource on the other domain, in order to determine whether the actual request is safe to send. Cross-site requests are preflighted like this since they may have implications to user data. In particular, a request is preflighted if: It uses methods other than GET or POST. Also, if POST is used to send request data with a Content-Type other than application/x-www-form-urlencoded, multipart/form-data, or text/plain, e.g. if the POST request sends an XML payload to the server using application/xml or text/xml, then the request is preflighted. It sets custom headers in the request (e.g. the request uses a header such as X-PINGOTHER)
事实上，由于安全原因，跨域AJAX (XMLHttp)请求是不允许的(考虑一下从客户端获取一个“受限”的网页并将其发送回服务器——这将是一个安全问题)。
唯一的解决方法是回调。这是:创建一个新的脚本对象，并将src指向端JavaScript，这是一个带有JSON值的回调(myFunction({data})， myFunction是一个对数据做一些事情的函数(例如，将其存储在变量中)。
只需将“application/json”更改为“text/plain”，不要忘记json .stringify(request):
var request = {Company: sapws.dbName, UserName: username, Password: userpass};
console.log(request);
$.ajax({
type: "POST",
url: this.wsUrl + "/Login",
contentType: "text/plain",
data: JSON.stringify(request),
crossDomain: true,
});
我能够修复它与以下头的帮助
Access-Control-Allow-Origin
Access-Control-Allow-Headers
Access-Control-Allow-Credentials
Access-Control-Allow-Methods
如果你使用的是Nodejs，下面是你可以复制/粘贴的代码。
app.use((req, res, next) => {
res.header('Access-Control-Allow-Origin','*');
res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
res.header('Access-Control-Allow-Credentials', true);
res.header('Access-Control-Allow-Methods', 'GET, POST, PUT, PATCH');
next();
});
