第六题：说说JS运行机制及Event Loop

[kujian]

setTimeout(function() {
  console.log(1)
}, 0);
new Promise(function executor(resolve) {
  console.log(2);
  for( var i=0 ; i<10000 ; i++ ) {
    i == 9999 && resolve();
  }
  console.log(3);
}).then(function() {
  console.log(4);
});
console.log(5);

[kujian]

http://www.ruanyifeng.com/blog/2014/10/event-loop.html https://juejin.im/post/5ac715b8f265da23986780fe https://zhuanlan.zhihu.com/p/52114921