https://stackoverflow.com/questions/35588699/response-to-preflight-request-doesnt-pass-access-control-check
    总结来说，前端调试时可以分为以下解决方案

    1. Turn off CORS. 关闭浏览器cors，不太推荐
    2. 安装浏览器插件解决，如 allow-control-allow-origin 具体可以在google商城搜索
    3. Use a proxy such as nginx 本地nginx 服务解决跨域，主要配置如下
    4. 服务端增加配置，需要服务端配合

    目前比较推荐使用第二种方案

    1. upstream api_server {
    2.     server apiserver.com;
    3. }
    5. server {
    6.         charset UTF-8;
    7.         listen 80;
    8.         root /home/web/myclient;
    9.         index index.html;
    10.         server_name myclient.com;
    12.         location /api/ {
    13.                 proxy_set_header X-Real-IP $remote_addr;
    14.                 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    15.                 proxy_set_header X-NginX-Proxy true;
    16.                 proxy_pass http://api_server/;
    17.                 proxy_ssl_session_reuse off;
    18.                 proxy_set_header Host $http_host;
    19.                 proxy_redirect off;
    20.         }
    22.         location ~ /\. {
    23.                 deny all;
    24.         }
    26.         location / {
    27.                 try_files $uri;
    28.         }
    29. }