fetch请求，跨域报错，mode: "no-cors"？
http://localhost:3000访问http://localhost:8080/a/b接口，报错“Failed to load http://localhost:8080/a/b: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:3000' is therefore not allowed access. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.”
这个报错是什么意思？？
我如果在请求中加入参数“
mode: "no-cors"
”就能正常访问了，这个
mode: "no-cors"是什么意思？起到什么作用？
还有，响应的status=200,可是response.ok是false，response.ok不应该是true吗？难道我要根据status判断请求是否成功？
请大佬赐教！万分感谢！
查看28道真题和解析