Refactored file structure and removed unnecessary code

js/arena.js

@@ -0,0 +1,35 @@
+class Arena {
+    constructor(gameInfo, game) {
+        this.g = gameInfo;
+        this.game = game;
+        this.field = createMatrix(this.g.fieldSize.x, this.g.fieldSize.y);
+    }
+
+    clearScreen() {
+        this.g.context.clearRect(0, 0, this.g.canvas.width, this.g.canvas.height);
+    }
+
+    sweep() {
+        let rowCount = 1;
+        outer: for (let y = this.field.length - 1; y > 0; --y) {
+            for (let x = 0; x < this.field[y].length; ++x) {
+                if (this.field[y][x] === 0) {
+                    continue outer;
+                }
+            }
+
+            const row = this.field.splice(y, 1)[0].fill(0);
+            this.field.unshift(row);
+            ++y;
+
+            this.p.score += rowCount * 10;
+            rowCount *= 2;
+        }
+        if (this.p.score - this.g.prevUpdateScore > 50) {
+            this.g.dropInterval -= 20;
+            this.g.dropInterval = this.g.dropInterval > 100 ? this.g.dropInterval : 100;
+            this.g.prevUpdateScore = this.p.score;
+        }
+        this.game.drawArena();
+    }
+}