javascript求数组的最大最小值

<script type="text/javascript">
var arr=[21,2,34,22,5,7,23,63,212,324,56,6,8,32,12,34,2,334344,22,5,7,23,63,212,324,56,6,123,345,1233,56,127,84,123,13,344,324,12,5,1,6,1,7,2,123,6512,323,97,434];
//数组按从大到小排序
arr.sort(function(a,b){return b-a;}); 
 
//求数组中最大值，最小值


// 方法一
Array.prototype.max=function(){
 var r=this.sort(function(a,b){return a-b;})
 return r[r.length-1];
 }
Array.prototype.min=function(){
 var r=this.sort(function(a,b){return a-b;})
 return r[0];
 }

// 方法二
Array.prototype.max=function(){
 var max = this[0];
    var len = this.length; 
    for (var i = 1; i < len; i++){ 
    if (this[i] > max) { 
       max = this[i]; 
    } 
    } 
    return max;
 }
 
Array.prototype.min = function() {
    var min = this[0];
    var len = this.length;
    for (var i = 1; i < len; i++){ 
       if (this[i] < min){ 
            min = this[i]; 
               } 
        } 
    return min;
   } 
  
 
//方法三
Array.prototype.max = function(){
      return Math.max.apply({},this);
} 
 
Array.prototype.min = function(){
      return Math.min.apply({},this)
}  
 
 
console.time("aa");  
var maxNum=arr.max();
console.timeEnd("aa");
alert(maxNum);


</script>