js关于字符串的两道题

1.编写函数rightchange(char,n),实现字符串char 循环右移n位

  function rightchange(char,n){
       var arr = char.split("");
       n = n % arr.length;//取余
       for(var i=1;i<=n;i++){
          arr.unshift(arr.pop());
       }
       console.log(arr.join(""));
  }
 rightchange("abcdefg",8);   

2 编写函数maxr(char)返回字符串char中最长的连续重复字母

 function maxr(char){
        var a = 0;
        var b=1;

        var maxlength = 0;
        var maxchar = "";

        while(a<=char.length-2){
            if(char.charAt(a) == char.charAt(b)){
                b++;
            }else{
               if(b-a>maxlength){
                  maxlength = b-a;
                  maxchar = char.slice(a,b);
               }
               a = b;
               b = a+1;
            }
        }
        console.log(maxchar,maxlength);
    }
     var str = "mmjiiikkkmmmmmmmmllllllllllllllllllmlll"
     maxr(str);