var num1=1,num2=2; function cal(){ var num1=10,num2=20; console.log(this.num1+this.num2); } var calBind=cal.bind({num1:100,num2:200}); new cal(); cal(); new calBind(); calBind(); 笔试遇到这道题,请问各位大佬输出为什么是 NaN NaN NaN 300 不理解前三个为啥都是NaN,是this的问题吗?