Why not just have a library in Javascript, for example:

  Q.each(arr, function(i) {
     this.rocks();
     arr.pop(); // watch out doing this in the loop
     arr.push('foo'); // watch out doing this in the loop
  });

  Q.each(obj, function(k) {
     this.rocks();
     delete obj[k]; // should be safe maybe
  });

  var p = Q.pipe(crazy stuff involving pipes and callbacks)
  doSql("SELECT * FROM users", p.fill('users'));

  getUsers = Q.getter(getUsers); // turns it into a really  smart getter

  getUsers = Q.batch(getUsers); // turns into into a batched getter

and lots of other stuff

Why must the language take care of everything for you when libraries can do it? That has been the case with C, C++ and other languages.