String.prototype.len=function()         
 {                 
    return this.replace(/[^\x00-\xff]/g,"rr").length;          
 }
         
 String.prototype.sub = function(n)
  {    
       var r = /[^\x00-\xff]/g;    
       if(this.replace(r, "mm").length <= n) return this;   
       // n = n - 3;    
       var m = Math.floor(n/2);    
       for(var i=m; i<this.length; i++) {    
       if(this.substr(0, i).replace(r, "mm").length>=n) {    
       return this.substr(0, i) ; }    
      } return this;   
 };