CORS in nginx

if ($request_method = 'OPTIONS') {
			add_header 'Access-Control-Allow-Origin' "$http_origin";
			add_header 'Access-Control-Allow-Credentials' 'true';
			add_header 'Access-Control-Allow-Methods' 'GET, POST,PUT,DELETE,OPTIONS';
			add_header 'Access-Control-Allow-Headers' 'Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Origin,Accept';
			add_header 'Content-Type' 'application/json';
			add_header 'Content-Length' 0;
 
			return 204;
		}