Question

我正在尝试实现async / await模块。在function2中，如果用户不在，我想在那里停止执行。我不想执行功能3，如果用户在场，我想执行function3

    const function1() {
                 //code
                 return a
                }

    const function2= (a,email) => model.user.findOne({ email:email}).then((user) => {
                    if (!user) {
                        ****// want to stop execution here****
                    } else {
                        //update details of user
                    }

                    return dealer;
                });


 const function 3 = function(dealer) {
            //mail sending
   };

 exports.mailer = async(email,callback) => {
                try {
                    var a =await function1();
                    var dealer =await function2(a,email);  //stop execution here       
                    var res  = await function 3(dealer);
                        await callback(res);
                    }catch (err){
                      callback(err);
                    }
                }

Answer 1

在function2中返回一个新的Promise，如果找到了一个用户就会解析，如果没有找到则拒绝你应该实现你想要的东西。像这样：

const function1 = () => {
    return a
}

const function2 = (a, email) => {
    return new Promise((resolve, reject) => {
        model.user.findOne({
            email: email
        }).then((user) => {
            if (!user) {
                // want to stop execution here****
                reject(new Error('Error Message'))
            } else {
                // update details of user
                resolve(dealer)
            }
        })
    })
}

const function3 = (dealer) => {
    //mail sending
}

exports.mailer = async (email, callback) => {
    try {
        var a = await function1()
        var dealer = await function2(a, email) // stop execution here
        var res = await function3(dealer)
        await callback(res)
    } catch (err) {
        callback(err)
    }
}

在节点js中使用async await？

1 个答案: