SOURCE

var globaVariabel1=0;
function test1(){
    var localVariablel1=2;
document.write(globaVariabel1+"<br/>");
document.write(localVariablel1+"<br/>");
}

test1();

var globaVariabel2=1;

function test2(){
    var localVariablel2=3;
}
test2();



document.write("<br/>-------------------<br/>");
function welcomeMes(){
    alert("Welcome");
}

function add(left,right){
    return left+right;
}
document.write(add(1,2)+3+"<br/>")

document.write("<br/>-------------------<br/>");

function isLeapYear(year){
     if ((year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0)) 
            {
                return year + "年是闰年";
            }
            else
            {
                return year + "年不是闰年";
            }
}
document.write(isLeapYear(2020)+"<br/>");
document.write(isLeapYear(2000)+"<br/>");
document.write(isLeapYear(2001)+"<br/>");

document.write("<br/>-------------------<br/>");

function getMax(a,b,c,d){
    var maxNum;
    maxNum=(a>b)?a:b;
    maxNum=(maxNum>c)?maxNum:c;
    maxNum=(maxNum>d)?maxNum:d;
    return maxNum;
}
    document.write("5个数最大值为："+getMax(4,2,8,7));

    document.write("<br/>-------------------<br/>");
 function max(arr){
     var ret = arr[0];
     for(var i  = 0 ; i <arr.length;i++){
       if(arr[i]>ret){
         ret = arr[i];
       }
     }
     return ret;
   }
function min(arr){
    var ret = arr[0];
    for(var i  = 0 ; i <arr.length;i++){
      if(arr[i]<ret){
        ret = arr[i];
      }
    }
    return ret;
  }
    var arr = [1,8,3,46,56,];
  document.write("最大值为："+max(arr)+"<br/>");  // 最大
  document.write("最小值为："+min(arr));// 最小