Repeating a function using setTimeout rather than setInterval

repeat.js

// Poll repeatedly. Use setTimeout rather than setInterval
// to ensure previous execution has completed before enqueing a new one

(function repeat() { 
    do_something();
    setTimeout(repeat, 2000);
})();

// The repeat function's scope is limited, so one can have multiple blocks like this
// without them interfering - and can wrap this in a helper function in the style of
// setInterval:

function setSafeInterval(callback, millis) {
  (function repeat() { 
      callback();
      setTimeout(repeat, millis);
  })();
}