用javaScript实现跟C#中类似的StringBuilder的功能

///<summary>
///声明一个相当于C#类StringBuilder
///</summary>
function StringBuilder()
{
    this._string=new Array();
}
///<summary>
///声明一个方法,连接字符串
///</summary>
///<param name=str>要连接的字符串</param>
StringBuilder.prototype.append=function(str)
{
 this._string.push(str);
}
///<summary>
///声明一个方法,获得字符串
///</summary>
StringBuilder.prototype.toString=function()
{
 return this._string.join("");
}
//获取字符数组
StringBuilder.prototype.ToCharArray=function()
{
return this.split("");
}
//获取N个相同的字符串
StringBuilder.prototype.Repeat=function(num)
{
var tmpArr=[];
for(var i=0;i<num;i++) tmpArr.push(this);
return tmpArr.join("");
}
//逆序
StringBuilder.prototype.Reverse=function()
{
return this.split("").reverse().join("");
}
//测试是否是数字
StringBuilder.prototype.IsNumeric=function()
{
var tmpFloat=parseFloat(this);
if(isNaN(tmpFloat)) return false;
var tmpLen=this.length-tmpFloat.toString().length;
return tmpFloat+"0".Repeat(tmpLen)==this;
}
//测试是否是整数
StringBuilder.prototype.IsInt=function()
{
if(this=="NaN") return false;
return this==parseInt(this).toStringBuilder();
}
// 合并多个空白为一个空白
StringBuilder.prototype.resetBlank = function()
{
return this.replace(/s+/g," ");
}
// 除去左边空白
StringBuilder.prototype.LTrim = function()
{
return this.replace(/^s+/g,"");
}
// 除去右边空白
StringBuilder.prototype.RTrim = function()
{
return this.replace(/s+$/g,"");
}
// 除去两边空白
StringBuilder.prototype.trim = function()
{
return this.replace(/(^s+)|(s+$)/g,"");
}
// 保留数字
StringBuilder.prototype.getNum = function()
{
return this.replace(/[^d]/g,"");
}
// 保留字母
StringBuilder.prototype.getEn = function()
{
return this.replace(/[^A-Za-z]/g,"");
}
// 保留中文
StringBuilder.prototype.getCn = function()
{
return this.replace(/[^u4e00-u9fa5uf900-ufa2d]/g,"");
}
// 得到字节长度
StringBuilder.prototype.getRealLength = function()
{
return this.replace(/[^x00-xff]/g,"--").length;
}
// 从左截取指定长度的字串
StringBuilder.prototype.left = function(n)
{
return this.slice(0,n);
}
// 从右截取指定长度的字串
StringBuilder.prototype.right = function(n)
{
return this.slice(this.length-n);
}
// HTML编码
StringBuilder.prototype.HTMLEncode = function()
{
var re = this;
var q1 = [/x26/g,/x3C/g,/x3E/g,/x20/g];
var q2 = ["&","<",">"," "];
for(var i=0;i<q1.length;i++)
re = re.replace(q1[i],q2[i]);
return re;
}
// Unicode转化
StringBuilder.prototype.ascW = function()
{
var strText = "";
for (var i=0; i<this.length; i++) strText += "&#" + this.charCodeAt(i) + ";";
return strText;
}

var strBuilder=new StringBuilder()
strBuilder.app("abc")
strBuilder.app("abc")
strBuilder.toString()