如何导航promises？

Question

我想得到一个承诺的第二个项目。我尝试过执行Promise.first(2)，但它返回undefined，与Promise.last(-3)一样。我看过Promise.race()和Promise.any()，但它看起来不像我需要的。如果可以这样做那就太好了。

const Promise = await // Promise
for (item in Promise) {
    console.log('Promise is ' + Promise.first(item));
    
}

有没有办法买到一件特别的东西？

promise包含多个具有不同值的项

Message {
channelId: '873969937230757938',
guildId: '873965279665860628',
deleted: false,
id: '905766388323467275',
type: 'DEFAULT',
system: false,
content: '',
author: User {
id: '530032883486687243',
bot: false,
system: false,
flags: UserFlags { bitfield: 128 },
username: 'Johnathan',
discriminator: '7301',
avatar: '8573a365f3c81903bb343bc9c2cd2c32'
},
pinned: false,
tts: false,
nonce: null,
embeds: [],
components: [],
attachments: Collection(0) [Map] {},
stickers: Collection(0) [Map] {},
createdTimestamp: 1636021935302,
editedTimestamp: 1636039356685,
reactions: ReactionManager { message: [Circular *1] },
mentions: MessageMentions {
everyone: false,
users: Collection(0) [Map] {},
roles: Collection(0) [Map] {},
_members: null,
_channels: null,
    crosspostedChannels: Collection(0) [Map] {},
repliedUser: null
},
webhookId: null,
  groupActivityApplication: null,
applicationId: null,
activity: null,
flags: MessageFlags { bitfield: 0 },
reference: null,
interaction: null

Answer 1

Promise本身并不包含值，它是未来数据的promise

下面是几个如何从其中检索数据示例

​

const promise = new Promise((resolve) => { // just a promise that return value after 1 second 
 setTimeout(() => resolve([1, 2, 3]), 1000)
})

async function readDataFromPromise(promise) {
  const data = await promise
  console.log('from function', data)
}

promise.then(data => console.log('from then', data))

readDataFromPromise(promise)

​