var PREV = 0
  , NEXT = 1
  , SKIP = 2
  , HALT = 3;

var insts = [PREV,SKIP,NEXT,SKIP,HALT,NEXT,NEXT]
  , arr   = []
  , ptr   = 0
  , cur   = 0;

for (var i = 0; i < 10*1000; i++)
  arr[i] = false;

// ----------

while (true) {
  var op = insts[cur];

  if (op == HALT) break;
  if (op == PREV) ptr = ptr == 0 ? arr.length-1 : ptr-1;
  if (op == SKIP && !arr[ptr]) cur++;
  if (op == NEXT) {
    ptr = ptr == arr.length-1 ? 0 : ptr+1;
    arr[ptr] = !arr[ptr];
  }

  cur = (cur+1) % insts.length;
}

console.log('Done');