参考回答:
setTimeout(function(){console.log(1)},0);new Promise(function(resolve,reject){console.log(2);resolve();}).then(function(){console.log(3)}).then(function(){console.log(4)});process.nextTick(function(){console.log(5)});console.log(6);//输出2,6,5,3,4,1
为什么呢?具体请参考我的文章:从promise、process.nextTick、setTimeout出发,谈谈Event Loop中的Job queue



