javascript - 对预检请求的响应未通过 NodeJS 中的访问控制检查

Question

即使我在 NodeJS/ExpressJS 中添加了以下代码，我也无法说服为什么会遇到以下错误。

XMLHttpRequest cannot load http://localhost:9000/polymer/105724/apply. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8080' is therefore not allowed access.

res.setHeader("Access-Control-Allow-Origin", "*");
res.setHeader('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
res.setHeader("Access-Control-Allow-Headers", "X-Requested-With, Content-Type");

Answer 1

您还需要允许OPTIONS方法。浏览器在实际调用之前发送 OPTIONS 调用，因此如果不允许 OPTIONS ，则不会进行下一次调用。

res.setHeader('Access-Control-Allow-Methods', 'OPTIONS,GET,PUT,POST,DELETE');