// 返回字符的长度，一个中文算2个
String.prototype.ChineseLength=function()
{ 
  return this.replace(/[^\x00-\xff]/g,"**").length;
}
// 判断字符串是否以指定的字符串结束
String.prototype.EndsWith = function(str) 
{
  return this.substr(this.length - str.length) == str;
}
// 去掉字符左端的的空白字符
String.prototype.LeftTrim = function()
{
  return this.replace(/(^[\\s]*)/g, "");
}
// 去掉字符右端的空白字符
String.prototype.RightTrim = function()
{
  return this.replace(/([\\s]*$)/g, "");
}
// 判断字符串是否以指定的字符串开始
String.prototype.StartsWith = function(str) 
{
  return this.substr(0, str.length) == str;
}
// 去掉字符两端的空白字符
String.prototype.Trim = function()
{
  return this.replace(/(^\s*)|(\s*$)/g, "");
}

// 为内部 String 对象添加方法
String.prototype.myMethod = function(){
 return "my define method";
}
// 为内部 String 对象重载方法
String.prototype.toString = function(){
 return "my define toString method";
}
var myObj = new String("foo");
alert(myObj.myMethod());
alert(myObj);
alert("foo".toString());

function Employee() {
 this.dept = "HR";
 this.manager = "John Johnson";
}
String.prototype = new Employee;
var myString = new String("foo");

object1.prototype.isPrototypeOf(0bject2);

function Person() {
 this.name = "Rob Roberson";
 this.age = 31;
}
function Employee() {
 this.dept = "HR";
 this.manager = "John Johnson";
}
Employee.prototype = new Person();
var Ken = new Employee();