apply和call进行精准匹配

求最大值

<script>
    var arr=[2,4,2,55,44,60]
    var max=Math.max.apply(null,arr)
    //applay执行函数max用数组的方式去传递
    console.log(max) //60
</script>

判断对象类型

<script>
    //判断对象类型比使用typeof更准确
 function getType(arg){
     var type=Object.prototype.toString.call(arg);
     return type.slice(8,-1)
 }
 console.log(getType([])) //Array
 console.log(getType(/a/g)) //RegExp
 console.log(getType(123)) //Number
 console.log(getType("")) //String
</script>