自定义对象：

1.定义并创建：

 people =new Object();
        people.name="iwen";
        people.age =30;
        document.write("name"+people.name+",age:"+people.age);
        people1={name:"iwen",age:"age"};
        document.write("name"+people1.name+",age:"+people1.age);

2.用函数创建： 
function people(name,age){
            this.name=name;
           this.age=age;
       }
        son=new people("iwen",30);
        document.write("name"+son.name+" age:"+son.age);

字符串对象：

length属性

var str="hello world";
        document.write(str.length);

输出11 说明包括空格

indexOf查找是否有串：

 var str="hello world";
        document.write(str.indexOf("world"));

输出6 没有输出-1

match()是否匹配 匹配 输出串 不匹配 输出-1

var str="hello world";
        document.write(str.match("world"));

输出world 
var str="hello world";
        document.write(str.match("world1"));
输出null

replace:

 var str="hello world";
        document.write(str.replace("world","jike"));

输出 hello jike


toUpperCase toLowerCase

字符串转化为数组（常用）

var str1="hello jike xuyuan";
        var s=str1.split(" ");
        document.write(s[1]);


Date：

当前时间：

var date=new Date();
        document.write(date);

输出： Thu Oct 29 2015 16:57:17 GMT+0800 (中国标准时间)

获取年份：

var date=new Date();
        document.write(date.getFullYear());

输出：2015

改变时间：

 var date=new Date();
       date.setFullYear(2013,1,1);
        document.write(date);

输出： Fri Feb 01 2013 17:00:29 GMT+0800 (中国标准时间)

时钟实例：：

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body οnlοad="startTime()">
    <script>
      function startTime()
      {
          var today=new Date();
          var h=today.getDate();
          var m=today.getHours();
          var s=today.getSeconds();
          h=checkTime(h);
          m=checkTime(m);
          s=checkTime(s);
        document.getElementById("timetest").innerHTML=h+";"+m+";"+s;
          t=setTimeout(function(){
              startTime();
          },500);
;      }
    function checkTime(i)
    {
        if(i<10) i+='0';return i;
    }
    </script>
<div id="timetest"></div>
</body>
</html>

数组

concat连接：

var a=["hello ","world"];
        var b=["iwen","ime"];
        var c= a.concat(b);
        document.write(c);

排序： 
 var a=["a ","b","c","t","b","e"];
        a.sort();
        document.write(a);
降序： 
var a=["1","3","2","6","4","9"];
        document.write(a.sort(function(a,b){
            return b-a;
        }));
貌似不能将字母降序排列==

结尾追加：

var a=["1","3","2","6","4","9"];a.push("c");
        document.write(a);

翻转： 


 var a=["1","3","2","6","4","9"];a.push("c");
        document.write(a.reverse());

Math

四舍五入：

document.write(Math.round(4.5));
随机数：返回0至1 
document.write(Math.random());
若是需要整数： 
document.write(parseInt(Math.random()*10));

最值： 
document.write(Math.max(20,10,14,33));

绝对值： 
document.write(Math.abs(-110));