Javascript 使用数组链接THEN
我正在寻找一种方法,将多个承诺链接在一起,类似于承诺。除了我希望每个人都等待最后一个。我相信这可能已经得到了回答,但我不知道该用谷歌搜索什么Javascript 使用数组链接THEN,javascript,node.js,Javascript,Node.js,我正在寻找一种方法,将多个承诺链接在一起,类似于承诺。除了我希望每个人都等待最后一个。我相信这可能已经得到了回答,但我不知道该用谷歌搜索什么 function output(msg) { return new Promise((resolve,reject) => { console.log(msg); resolve(); }); } output('1st').then(() => { output('2nd').then(() => { output(
function output(msg) {
return new Promise((resolve,reject) => {
console.log(msg);
resolve();
});
}
output('1st').then(() => {
output('2nd').then(() => {
output('3rd').then(() => {
console.log('done')
});
});
});
// I want to be able to build from an array of length n
const msgs = ['1st','2nd','3rd'];
for(let i = 0; i < msgs.length;i++){
// Not sure what to do here
output(msgs[i]).then(() => {
output(msgs[i+1]);
});
}
函数输出(msg){
返回新承诺((解决、拒绝)=>{
控制台日志(msg);
解决();
});
}
输出('1st')。然后(()=>{
输出('2nd')。然后(()=>{
输出('3rd')。然后(()=>{
console.log('done')
});
});
});
//我希望能够从长度为n的数组中进行构建
常数msgs=['1st','2nd','3rd'];
for(设i=0;i{
输出(msgs[i+1]);
});
}
您可以像这样将它们链接起来,以避免像地狱一样筑巢:
output('a')
.then(a_out => output('b'))
.then(b_out => output('c'))
.then(c_out => console.log('all done'));
对于一系列的承诺[]
:
let loopback = (arr, i=0) => {
return arr[i].then(() => {
if (i < arr.length - 1)
return loopback(arr, i+1);
});
};
let last = loopback(load);
let loopback=(arr,i=0)=>{
返回arr[i],然后(()=>{
如果(i
您可以在数组上使用类似循环的forEach
,并在异步函数中使用wait
:
function output(msg) {
return new Promise((resolve,reject) => {
console.log(msg);
resolve();
});
}
const msgs = ['1st','2nd','3rd'];
function ArrPromiseAll(arr) {
arr.forEach(async function(i) {
await output(i);
});
console.log("Done All.");
}
ArrPromiseAll(msgs);
产出:
1st
2nd
3rd
Done All.
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