add basic keyboard controls

main.js

@@ -5,12 +5,18 @@ const Orientation = {
   RIGHT: 'right'
 }
 
+// TODO: make these not global.
+let upArrowPressed = false;
+let downArrowPressed = false;
+let leftArrowPressed = false;
+let rightArrowPressed = false;
+
 class Input {
   constructor() {
-    this.left = false;
-    this.right = false;
     this.up = false;
     this.down = false;
+    this.left = false;
+    this.right = false;
     this.a = false;
     this.b = false;
     this.x = false;
@@ -20,25 +26,60 @@ class Input {
     this.select = false;
     this.start = false;
 
-    this.leftArrowPressed = false;
-    this.rightArrowPressed = false;
     window.addEventListener('gamepadconnected', this.gamepadConnected);
     window.addEventListener('gamepaddisconnected', this.gamepadDisconnected);
+    document.addEventListener('keydown', this.keyDown);
+    document.addEventListener('keyup', this.keyUp);
+  }
+
+  keyDown(e) {
+    if (e.key == 'ArrowUp' || e.key == 'w') {
+      upArrowPressed = true;
+    }
+    if (e.key == 'ArrowDown' || e.key == 's') {
+      downArrowPressed = true;
+    }
+    if (e.key == 'ArrowLeft' || e.key == 'a') {
+      leftArrowPressed = true;
+    }
+    if (e.key == 'ArrowRight' || e.key == 'd') {
+      rightArrowPressed = true;
+    }
+  }
+
+  keyUp(e) {
+    if (e.key == 'ArrowUp' || e.key == 'w') {
+      upArrowPressed = false;
+    }
+    if (e.key == 'ArrowDown' || e.key == 's') {
+      downArrowPressed = false;
+    }
+    if (e.key == 'ArrowLeft' || e.key == 'a') {
+      leftArrowPressed = false;
+    }
+    if (e.key == 'ArrowRight' || e.key == 'd') {
+      rightArrowPressed = false;
+    }
   }
 
   update() {
     // TODO: have a config screen instead of hard-coding the 8Bitdo SNES30 pad.
     // TODO: handle connects / disconnects more correctly.
+
+    this.up = upArrowPressed;
+    this.down = downArrowPressed;
+    this.left = leftArrowPressed;
+    this.right = rightArrowPressed;
+
     const gamepad = navigator.getGamepads()[0];
     if (gamepad == null || !gamepad.connected || gamepad.axes.length < 2 ||
         gamepad.buttons.length < 12) {
       return;
     }
-
-    this.left = gamepad.axes[0] < 0;
-    this.right = gamepad.axes[0] > 0;
-    this.up = gamepad.axes[1] < 0;
-    this.down = gamepad.axes[1] > 0;
+    this.up |= gamepad.axes[1] < 0;
+    this.down |= gamepad.axes[1] > 0;
+    this.left |= gamepad.axes[0] < 0;
+    this.right |= gamepad.axes[0] > 0;
     this.a = gamepad.buttons[0].pressed;
     this.b = gamepad.buttons[1].pressed;
     this.x = gamepad.buttons[3].pressed;