从 then/catch promises 链迁移到 async/await

Question

我正在尝试将承诺链 .then().catch 转换为异步/等待函数

const chain = [
    {
        onFulfilled: () => {/*some logic*/},
        onRejected: () => {/*some logic*/},
    {
        onFulfilled: () => {/*some logic*/},
        onRejected: () => {/*some logic*/},
    {
        onFulfilled: () => {/*some logic*/},
        onRejected: () => {/*some logic*/},
    },
    //...
];
const data = 'initial data';
let promise = Promise.resolve(data);
let i = 0;
while (i < chain.length) {
    promise = promise.then(chain[i].onFulfilled).catch(chain[i].onRejected);
    i++;
}

最终承诺等于：

promise = Promise.resolve()
.then(chain[0].onFulfilled).catch(chain[0].onRejected)
.then(chain[1].onFulfilled).catch(chain[1].onRejected)
.then(chain[2].onFulfilled).catch(chain[2].onRejected)
....

这是我到目前为止尝试过的

let data = 'initial data';
for (const fn of chain) {
  try {
      data = await fn.onFulfilled(data);
  } catch (e) {
      data = await fn.onRejected(e);
  }
}

问题是：如果 fn.onRejected 抛出一个错误，错误导致 for 循环停止而不是被下一个 fn.onRejected 处理

Answer 1

您可以使用

while

循环简化

for..of

混乱 -

let p = Promise.resolve(initialData)
for (const {onFulfilled, onRejected} of chain)
  p = p.then(onFulfilled, onRejected)

与-

相同

const p = chain.reduce(
  (acc, {onFulfilled, onRejected}) =>
    acc.then(onFulfilled, onRejected),
  Promise.resolve(initialData)
)

我认为您为此使用

async..await

不会有任何收获。正如您已经指出的那样，由于

try..catch

.

，它引入了更多的复杂性