// JScript 文件
/**  
 * StringBuffer Class, to join two string is the most use  
 * @author xiaofei 2007-7-20   
 */  
function StringBuffer()   
{   
    this._strings = [];   
    if(arguments.length==1)   
    {   
        this._strings.push(arguments[0]);   
    } 
    
    StringBuffer.prototype.append = function(str)   
{   
    this._strings.push(str);   
    return this;   
}   
  
StringBuffer.prototype.toString = function()   
{   
    return this._strings.join("");   
}   
  
/* 返回长度 */  
StringBuffer.prototype.length = function()   
{   
    var str = this._strings.join("");   
    return str.length;   
}   
  
/* 删除后几位字符 */  
StringBuffer.prototype.del = function(num)   
{   
    var len = this.length();   
    var str = this.toString();   
    str     = str.slice(0,len-num);   
    this._strings = [];   
    this._strings.push(str);   
}  
}