Pretty accurate ticker in JavaScript that runs code every # milliseconds

ticker.js

// Run code every # (here 200) milliseconds

function ticker() {
  var now = 0;
  var ticks = 0;
  var delta = 0;

  (function tick() {
    now = Date.now();

    ticks++;
    console.log(ticks);
    
    /*
      Code that can take quite a long time
      If it takes 200ms or more, the delta will be <= 0
      The next tick will be called without delay
    */
    
    delta = 200-(Date.now()-now)
    setTimeout(tick, delta);
  })();
}