JS实现获取数组中最大值或最小值功能示例

//最小值
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;
}
console.log([55,38,7,19].min());
//最大值
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;
}
console.log([55,38,7,19].max());

if(typeof Array.prototype['max'] == 'undefined'){
  Array.prototype.max = function(){...}
}

//最小值
Math.min.apply(Math,arr); //等效于 Math.min.apply({},arr)和Math.min.apply(null,arr);
//原本取得最小值的方法是Math.min(n1,n2,n3...), apply可以改变参数的传入形式，第一个参数是什么都不是很重要
//最大值
var arr = [55,38,7,19];
console.log(Math.max.apply(Math,arr));

var arr1 = [1,2,3,[5,6],[3,4,8]];
var arr2 = arr1.join(",").split(",");
var a = Math.min.apply(Math,arr2); 
console.log(a);

var arr = [55,38,7,19];
function getMaxMin(arr,maxmin){
  if(maxmin === "max"){
    return Math.max.apply(Math,arr);
  }else if(maxmin === "min"){
    return Math.min.apply(Math,arr);
  }
}
var a = getMaxMin(arr,"max");
console.log(a);
var b = getMaxMin(arr,"min");
console.log(b);