timeout vs promise timeout in ev
2018-07-30 本文已影响10人
超薄智能
console.log('---start---');
const timeOut = (val,wait)=>{
setTimeout(()=>{
console.log(val?val:"timeout");
},(wait?wait:0));
}
const fPromise = (parm)=>{
return new Promise((resolve,reject)=>{
resolve(parm);
});
}
fPromise('Ptime0')
.then(val=>timeOut(val,0));
timeOut('time0',0);
timeOut('time1',1);
timeOut('time1.9',1.9);
timeOut('time2',2);
my excepted result
---start---
time0
Ptime0
time1
time1.9
time2
· result in my browser is bellow, and the result seems steady, but few times Ptime0 will become the last one.
· 2 millisecond is like the margin time for my computer to transfer the timeout from Micro Task Queue (the promise in) to the Task Queue
· but why the task in task Queue executed before the transfer process is done!! how could it be if is performed by sequence, and how could it be parallel in a single thread with event loop.
---start---
time0
time1
time1.9
Ptime0
time2
