How to remove consecutive and repeated characters from JS string

  var s = "1122333455";
     var s1 = s;
     var c;
     var cc = s.match(/(\d)\1+/g);    //11,22,333,55 当然这里用()\1*也会可以(因为下面是替换):11,22,333,4,55
     for(var i = 0;i<cc.length;i++){
         c = cc[i].substring(0,1);
         s1 = s1.replace(cc[i],c);
    }
    alert(s1);   //12345

     var s = "1234321abaccc";
     var s1 = s.split("").sort().join("");
     var cc = s1.match(/(.)\1+/g);    //11,22,33,aa,ccc 当然这里用()\1*也会可以(因为下面是替换):11,22,33,4,aa,b,ccc
     for(var i = 0;i<cc.length;i++){
         c = cc[i].substring(0,1);
         s1 = s1.replace(cc[i],c);
     }
    alert(s1);    //1234abc

function repeat(str , n){
return new Array(n+1).join(str);
}
console:
repeat("a", 3); //aaa

var sa="ABCD";
var newStr=Array.prototype.join.call(sa); //A,B,C,D
newStr.split(','); //['A','B','C','D']