code: function clear() {
          for (var that = _validateCollection(this, NAME), data = that._i, entry = that._f; entry; entry = entry.n) {
            entry.r = true;
            if (entry.p) entry.p = entry.p.n = undefined;
            delete data[entry.i];
          }
          that._f = that._l = undefined;
          that[SIZE] = 0;
        }
docs: 23.1.3.1 Map.prototype.clear() 23.2.3.2 Set.prototype.clear()