Javascript 为数组添加方法（求和，最大值）实例

//求和
Array.prototype.sum = function ()
{
 for (var sum = i = 0; i < this.length; i++)sum += parseInt(this[i]);
 return sum
};

//求最大值
Array.prototype.maxima = function ()
{
 for (var i = 0, maxValue = Number.MIN_VALUE; i < this.length; i++)parseInt(this[i]) > maxValue && (maxValue = this[i]);
 return maxValue
};

//应用
var arr = [1,21,3,4,22,45,6,7,32];
alert(arr.join("+") + "=" + arr.sum()); //和：141
alert(arr.join("|") + "中, 最大的数是:" + arr.maxima()); //最大数：45
</script>

//-----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)
}