JavaScript execution wow and flutter

flutter.js

// 2016-11-29 jorge@jorgechamorro.com
// JavaScript execution wow and flutter

var MAX_ms= -1;
var r, now, ctr, str;
var MAX_ctr= -1;
var MIN_ctr= 10e9;

function sync (now,r) {
  now= Date.now()+ 1;
  while ( now > ( r= Date.now() ) ) ;
  return r;
}

do {
  ctr= 0, now= sync();
  do ctr+= 1; while ( now === ( r= Date.now() ) );
  r= r-now;
  str= '';
  if (r > MAX_ms) MAX_ms= r;
  if (ctr < MIN_ctr) MIN_ctr= ctr;
  if (ctr > MAX_ctr) MAX_ctr= ctr;
  str= 'MAX_ms:'+ MAX_ms+ ' MIN_ctr:'+ MIN_ctr+ ' MAX_ctr:'+ MAX_ctr+ '\r';
  process.stdout.write(str);
} while (1);