Answers for "has been blocked by CORS policy: No 'Access-Control-Allow-Origin'"

origin 'http://localhost:4200' has been blocked by CORS policy

let headers = new HttpHeaders({
      'Content-Type': 'application/json',
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Headers': 'Content-Type',
      'Access-Control-Allow-Methods': 'GET,POST,OPTIONS,DELETE,PUT',
      'Authorization': 'Bearer szdp79a2kz4wh4frjzuqu4sz6qeth8m3',
    });

allow cross origin

Access-Control-Allow-Origin: *
Access-Control-Allow-Origin: <origin>
Access-Control-Allow-Origin: null

origin 'http://localhost:4200' has been blocked by CORS policy

'Content-Type': 'application/json',
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Headers': 'Content-Type',
      'Access-Control-Allow-Methods': 'GET,POST,OPTIONS,DELETE,PUT',
      'Authorization': 'Bearer key',

loi Access-Control-Allow-Origin

open -n -a /Applications/Google Chrome.app/Contents/MacOS/Google Chrome --args --user-data-dir="/tmp/chrome_dev_test" --disable-web-security