如何 return 数据和承诺

Question

此函数像状态机一样按顺序处理股票账户数据，以便下卖单。

我需要将帐户数据传递给每个州，我不想将其存储在全局变量中。我该如何实现？我是否不恰当地使用了承诺？

注意像get_account、delete_order这样的每个调用都是returns承诺的异步调用.他们不应该传递不相关的数据。

function sell_stocks(){
    get_account_info().then(account => {
        if (account.orders.length > 0){
            return delete_orders(account.orders);
        } else {
            return "continue";
        }
    }).then(data => {
        // Now I need variable "account"
        place_sell_order(account.volume); //account undefined
    }).catch(msg => {
        //handle error
    });
}

Answer 1

干什么

return delete_orders(account.orders).then((data) => [data,account]);

和

then(([data, account]) => {...})

或者如果您只想要帐户数据

return delete_orders(account.orders).then(() => account);

和

function sell_stocks(){
    get_account_info().then(account => {
        if (account.orders.length > 0){
            return delete_orders(account.orders).then(()=> account);
        } else {
            return account;
        }
    }).then(account => {
        place_sell_order(account.volume);
    }).catch(msg => {
        //handle error
    });
}

或 async/await

async function sell_stocks(){
  try {
    const account = await get_account_info();
    if (account.orders.length > 0) {
      await delete_orders(account.orders)
    }
    return place_sell_order(account.volume);
  } catch (e) {
    console.log(`At sell_stocks ${e}`);
    return null;
  }
}

Answer 2

Return account 从第一个 .then() 到链接 .then()

访问 account

function sell_stocks(){
    return get_account_info().then(account => {
        if (account.orders.length > 0){
            return account
        } else {
            return "continue";
        }
    }).then(data => {
        // Now I need variable "account"
        return delete_orders(data.orders)
               .then(() => place_sell_order(data.volume))
    }).catch(msg => {
        //handle error
    });
}

Answer 3

您可以进行如下操作：

function sell_stocks() {
    get_account_info().then((account) => {
        return new Promise((resolve) => {
            if (account.orders.length > 0) {
                resolve(delete_orders(account.orders));
            } else {
                resolve('continue');
            }
        }).then(data => {
            // Now I need variable "account"
            place_sell_order(account.volume); //account undefined
        }).catch(msg => {
            //handle error
        });
    });
}

因此将 account 变量保留在本地范围内。

如何 return 数据和承诺

How to return data along with a promise

javascript

state-machine

node.js

es6-promise