Use Accept header for returning JSON instead of plain text

main.go

@@ -177,6 +177,12 @@ func main() {
 			return
 		}
 
+		// Does not handle multiple media types
+		if r.Header.Get("Accept") == "application/json" {
+			w.Header().Set("Content-Type", "application/json")
+			json.NewEncoder(w).Encode(departures)
+		} else {
+			// plain text
 			for _, d := range departures.Departures {
 				fmt.Fprintf(w, "%2s %-11s %6s\n",
 					d.Symbol,
@@ -184,6 +190,7 @@ func main() {
 					d.Leaving,
 				)
 			}
+		}
 	})
 	log.Fatal(http.ListenAndServe(":8000", nil))
 }