看这篇http://www.laruence.com/2009/09/23/1089.html
所以实际上 setTimeout更像是任务按照队列执行 经过setTimeout设置后任务放在了队尾
function a(){
setTimeout(function(){
console.log('timeout');
},0);
console.log('a');
}
function b(){
setTimeout(function(){
console.log('timeout1000');
},1000);
console.log('b');
}
function c(){
console.log('c');
}
a();
b();
c();
执行结果
a
b
c
timeout
timeout1000