我需要同步运行startFunc功能,并在for循环来完成任务,再次运行“等待”。我不能在startFunc使用的await()。我需要在C#我像.wait(),除了结果:开始1月底1日开始2月底2等..
function callToDB(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}
async function startFunc (i) {
console.log('start', i);
await callToDB(1000);
console.log('end', i);
}
for (let i = 0; i < 5; i++) {
startFunc(i);
}
你需要把for
环在async
功能为好,这样你就可以await
每次调用startFunc
:
function callToDB(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}
async function startFunc (i) {
console.log('start', i);
await callToDB(1000);
console.log('end', i);
}
(async () => {
for (let i = 0; i < 5; i++) {
await startFunc(i);
}
})();
另一种方法是不断链.then
s:
function callToDB(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}
async function startFunc (i) {
console.log('start', i);
await callToDB(1000);
console.log('end', i);
}
let prom = Promise.resolve();
for (let i = 0; i < 5; i++) {
prom = prom.then(() => startFunc(i));
}
或者你可以使用.reduce
,沿着过去的承诺不断传递的蓄电池,而不是分配给外部变量:
function callToDB(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}
async function startFunc (i) {
console.log('start', i);
await callToDB(1000);
console.log('end', i);
}
const finalProm = Array.from({ length: 5 })
.reduce(
(lastProm, _, i) => lastProm.then(() => startFunc(i)),
Promise.resolve()
);