Test例子里的 if( 'touches' in cc.sys.capabilities )是什么意思哩

Cocos2d-x JavaScript
#1 
  if( 'touches' in cc.sys.capabilities )//这句看不懂呀，新手求指点，官方TEST的，ClickAndMoveTest.js里
        cc.eventManager.addListener(cc.EventListener.create({
            event: cc.EventListener.TOUCH_ALL_AT_ONCE,
            onTouchesEnded:function (touches, event) {
                if (touches.length <= 0)
                    return;
                event.getCurrentTarget().moveSprite(touches.getLocation());
            }
        }), this);
#2

帮你顶上去 我也想知道

#3

for (var key in cc.sys.capabilities){cc.log(“key:”+key);}
用这个东西可以看到里面有什么

在桌面端 我输出的是：
key:canvas
key:mouse
key:keyboard
key:accelerometer

#4

在ipad端输出

key:canvas
key:opengl //移动端也多了这个
key:touches //这个就是touch事件了
key:mouse
key:keyboard
key:accelerometer

#5

用破三星机打开

key:canvas
key:touches //看来touch事件是移动端独有的
key:mouse
key:keyboard
key:accelerometer