jssubstring从右边获取指定长度字符串(示例代码)

 /*

  Gettherightmostsubstring,ofthespecifiedlength,

  fromaStringobject.

*/ 

String.prototype.right=function(length_) 

{ 

       var_from=this.length-length_; 

       if(_from<0)_from=0; 

       returnthis.substring(this.length-length_,this.length); 

};