Object recursive loop, detects infinite recursion

recurseloop.js

function objectLoop(obj, callback) {
  if (!obj) return null;
  var it, key, l, currobj = {
      obj: obj,
      keys: Object.keys(obj),
      index: 0
    },
    nest = [];
  mai: while (currobj) {
    sec: while (currobj.index < currobj.keys.length) {
      it = currobj.obj[key = currobj.keys[currobj.index++]];
      if (it && typeof it == "object") {
        l = nest.push(currobj);
        while (l--) {
          if (nest[l].obj === it) {
            callback.call(currobj.obj, it, key, nest.length - 1)
            currobj = nest.pop();
            continue sec;
          }
        }
        callback.call(currobj.obj, it, key, nest.length - 1, true);
        currobj = {
          obj: it,
          keys: Object.keys(it),
          index: 0
        };
        continue mai;
      } else {
        callback.call(currobj.obj, it, key, nest.length)
      }
    }
    currobj = nest.pop();
  }
}