use constants for event emitter names

src/constants.js

@@ -12,3 +12,6 @@ export const ENDED = "ENDED";
 export const COOLDOWN = 250;
 export const SCORE_CAP = 150;
 export const SCORE_INCREASE = 10;
+
+export const EMIT_MOVE = "EMIT_MOVE";
+export const EMIT_NEW_GAME = "EMIT_NEW_GAME";

src/controls.js

@@ -1,6 +1,6 @@
 "use strict";
 
-import { UP, RIGHT, DOWN, LEFT } from "./constants";
+import { UP, RIGHT, DOWN, LEFT, EMIT_MOVE, EMIT_NEW_GAME } from "./constants";
 
 class EventEmitter {
   constructor() {
@@ -23,20 +23,20 @@ const events = new EventEmitter();
 import Mousetrap from "mousetrap";
 
 Mousetrap.bind("up", () => {
-  events.emit("move", { direction: UP });
+  events.emit(EMIT_MOVE, { direction: UP });
 });
 Mousetrap.bind("right", () => {
-  events.emit("move", { direction: RIGHT });
+  events.emit(EMIT_MOVE, { direction: RIGHT });
 });
 Mousetrap.bind("down", () => {
-  events.emit("move", { direction: DOWN });
+  events.emit(EMIT_MOVE, { direction: DOWN });
 });
 Mousetrap.bind("left", () => {
-  events.emit("move", { direction: LEFT });
+  events.emit(EMIT_MOVE, { direction: LEFT });
 });
 Mousetrap.bind("enter", () => {
-  events.emit("new_game");
+  events.emit(EMIT_NEW_GAME);
 });
-Mousetrap.bind("space", () => events.emit("new_game"));
+Mousetrap.bind("space", () => events.emit(EMIT_NEW_GAME));
 
 export default events;

src/game.js

@@ -1,6 +1,6 @@
 "use strict";
 
-import { IDLE, ENDED } from "./constants";
+import { IDLE, ENDED, EMIT_MOVE, EMIT_NEW_GAME } from "./constants";
 
 import canvas from "./html.js";
 import Snake from "./snake";
@@ -78,10 +78,10 @@ requestAnimationFrame(render);
 
 import controls from "./controls";
 
-controls.on("move", ({ direction }) => {
+controls.on(EMIT_MOVE, ({ direction }) => {
   s.setDir(direction);
 });
-controls.on("new_game", () => {
+controls.on(EMIT_NEW_GAME, () => {
   s.newGame();
   requestAnimationFrame(render);
 });