isNaN与Number.isNaN的区别

1、isNaN(val)
通过Number()强制类型转换 将val转成number类型，再判断是否为NaN
So isNaN()是判断val是否能转为数字

console.log(isNaN(null));            //false
console.log(isNaN(true));            //false
console.log(isNaN(false));           //false
console.log(isNaN(0));               //false
console.log(isNaN(undefined));       //true
console.log(isNaN("AB"));            //true
console.log(isNaN({a: 1}));          //true
console.log(isNaN(NaN));             //true

2、Number.isNaN()
Es6 新加的严格判断是否===NaN

console.log(Number.isNaN(null));      //false
console.log(Number.isNaN(true));      //false
console.log(Number.isNaN(false));     //false
console.log(Number.isNaN(0));         //false
console.log(Number.isNaN(undefined)); //false
console.log(Number.isNaN("AB"));      //false
console.log(Number.isNaN({a: 1}));    //false
console.log(Number.isNaN(NaN));       //true