其他功能完成后如何调用一个功能？

Question

My problem is that i coded a simple overstock function for my game-items trading site ( site working with socket.io! ). And when the site is loading, two functions getting user and site inventories with items and listing them into two boxes, but the user inv loads faster and info about overstock comes later as the bot inv is loaded. I need to execute the "get user inventory" function after the "get bot inventory" function is fully done. I tried to set a sleep function between them, but it worked only for the main function that loading whole functions. In other words sleep(2000) delays loading both inventories when it set between this two functions. sorry for my bad english :-D

Aaand there is my code (i left only important part):

io.on('connection', (socket) => {
    var userObject = false
    if (
        typeof socket.handshake.session.passport !== 'undefined' &&
        typeof socket.handshake.session.passport.user !== 'undefined' &&
        typeof socket.handshake.session.passport.user.id !== 'undefined'
    ) {
        userObject = socket.handshake.session.passport.user
    }

    socket.emit('site', config.site)
    socket.emit('user', userObject)

    socket.on('get bot inv', (id) => {
        Trade.getInventory(config.bots[id].steamID64, config.appID, config.contextID, (err, data) => {
            socket.emit('bot inv', { error: err, items: data })
        })
    })
   socket.on('get user inv', (steamID64) => {
        Trade.getInventory(steamID64, config.appID, config.contextID, (err, data) => {
            socket.emit('user inv', { error: err, items: data })
        })
    })
    socket.on('get bots inv', () => {
        const params = []
        Object.keys(config.bots).forEach((index) => {
            const bot = config.bots[index]
            params.push({
                id: index,
                steamID64: bot.steamID64,
                appID: config.appID,
                contextID: config.contextID,
            })
        })

        Trade.getInventories(params, (data) => {
            socket.emit('bots inv', data)
            socket.emit('bots floats', Trade.getFloatValues())
        })
    })
})

Answer 1

Look into promises.

var promise1 = new Promsie((resolve, reject) => {
  socket.on('get bot inv', (id) => {
        Trade.getInventory(config.bots[id].steamID64, config.appID, config.contextID, (err, data) => {
            socket.emit('bot inv', { error: err, items: data })
            resolve();
        })
    })
})

var promise2 = new Promsie((resolve, reject) => {
 socket.on('get user inv', (steamID64) => {
        Trade.getInventory(steamID64, config.appID, config.contextID, (err, data) => {
            socket.emit('user inv', { error: err, items: data })
            resolve();
        })
    })
})

If you want to wait until one finishes

promise1.then(() => {return promise2});

If you want N things to execute and await all of them, use the following

Promise.all([promise1, promise2]).then(() => {execute something else});

For further documentation:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all

Answer 2

You might want to use promises. At first, encapsulate the socket listeners and the API call with promises:

  const getUserId = new Promise(res => socket.on('get bot inv', res));
 const getBotId = new Promise(res => socket.on('get bot inv', res));

  function getInventory(id) {
    return new Promise((res, rej) => {
      Trade.getInventory(id, config.appID, config.contextID, (err, data) => {
        if(err) rej(err) else res(data);
    });
  }

Then its easy to chain the promises:

 (async function() {
   const userID = await getUserId;
   const data = await getInventory(userID);
   socket.emit({ data });

   const botID = await getBotId;
   const botData = await getInventory(config.bots[botID].steamID64);
   socket.emit({ botData });
 })();