function innerFn() {
  var start = new Date();
  console.log("inner function start");

  while(new Date() - start < 1000) {}
  console.log("use time ", new Date() - start, "ms");
  console.log("inner function finished");
}

function test() {
  var start = new Date();
  console.log("test function start");

  setTimeout(function() {
    console.log("setTimeout callback function execute, time: ", new Date() - start, "ms");
  }, 500);

  while(new Date() - start < 1000) {}
  console.log("first while loop finished");

  innerFn();

  var newStart = new Date();
  while(new Date() - newStart < 1000) {}
  console.log("second while loop finished");

  console.log("test function finished");
}