node.js承诺不会在if语句中解析

Question

Looking for some help with promises, why will resolve not work inside this if statement?

async getTrades() {
    return new Promise(function (resolve, reject) {
        if (this.exchange === 'GDAX') {
            resolve('fake')
            console.log('inside GDAX')
        }
    }.bind(this))
}

When I put the resolve outside the if statement (before or after), it works. And the console.log('inside GDAX') does fire, so this.exchange ==='GDAX' returns true.

Here is the function that calls it:

getHistoricalPortfolioReturn() {
    return new Promise(function (resolve, reject) {
        var exchange_trades_calls = []
        for (var exchange_account in this.exchange_accounts) {
            if (this.exchange_accounts.hasOwnProperty(exchange_account)) {
                exchange_trades_calls.push(this.exchange_accounts[exchange_account].getTrades())
            }
        }
        Promise.all(exchange_trades_calls)
        .then(function (trades) {
            console.log('resolved')
            console.log('trades: ' + trades)
            resolve(trades)
        })
        .catch(function (error) {
            console.error('error: ' + error)
        })
    }.bind(this))
}

Answer 1

You are using an async function. You do not have to return a promise as it will be automatically wrapped in a promise.

async getTrades() {
    if(this.exchange === 'GDAX')  return "fake";
}

tldr: You are resolving the incorrect promise.