text: (function (window) {
    'use strict';
  
    var levelArr = (function () {
      var arr = [0];
      for (var i = 0; i < 10; i++) {
        arr.push(Math.pow(2, i) * 10000);
      }
      return arr;
    })();
  
    function Level() {
      this.canvas = new Canvas('level', 100, 70);
      this.level = 1;
  
      this._init();
    }
  
    Level.prototype = {
      constructor: Level,
      _init: function () {
        this._render();
      },
      _render: function () {
        this.canvas.drawText('Level ' + this.level);
      },
      checkLevel: function (score) {
        if (score >= levelArr[this.level]) {
          this.level++;
          this._render();
          return this.level;
        }
        return 0;
      }
    };
  
    window.Level = Level;
  })(window);