问题一
Access to XMLHttpRequest at 'file:///E:/Ajax/db.json' from origin 'null' has been blocked by CORS policy: Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, https.
问题二
Access to XMLHttpRequest at 'http://locally.uieee.com/categories' from origin 'http://localhost:8000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.