work-in-animation-frame.js

function callFnOnListInFrames(scope, list, fn, args) {
  return new Promise(function(resolve, reject) {
    args = args || [];
    // var start = performance.now();
    var workInd = 0;
    var results = [];
    var start;
    var elapsed;
    
    function _workInOneFrame(now) {
      start = now;
      elapsed = 0;
      while (workInd < list.length && elapsed < 16) {
        results.push(fn.apply(scope, args.length ? args.concat([list[workInd]]) : [list[workInd]]));
        workInd++;
        elapsed = performance.now() - start;
      }
      
      if (workInd === list.length) {
        // We finished everything. Stop.
        return resolve(results);
      }
      window.requestAnimationFrame(_workInOneFrame);
    }
    
    window.requestAnimationFrame(_workInOneFrame);
  });
}

function count(a) {
  return `I counted ${a}`;
}

callFnOnListInFrames(null, ['1','2','3'], count, []).then((result) => //... );