javascript - Promise 和 Node 使变量在不同的函数中可用

Question

我有三个函数，我希望函数一和函数二中的变量在函数三中可用。

功能一

在函数一中，我尝试包含该变量 emailUser 来解析以在第三个函数中使用它。

var firstMethod = function() {
    var promise = new Promise(function(resolve, reject){
        setTimeout(function() {
            app.post('/api/data', function (req, res) {
                console.log(req.body);
                var emailUser = req.body.email;
                res.send(emailUser);
            });
            console.log('first method completed');
            resolve({data: emailUser });
        }, 2000);
    });
    return promise;
};

第二个函数

我试图传递此函数 api_key 以在第三个函数中使用。

var secondMethod = function(someStuff) {
    var promise = new Promise(function(resolve, reject){
        setTimeout(function() {
            nodePardot.PardotAPI({
                userKey: 34535345,
                email: fsf@dd.com,
                password: fd3sv34f,
                DEBUG: true
            }, function (err, client) {
                if (err) {
                    // Authentication failed
                    console.error("Authentication Failed", err)
                } else {
                    // Authentication successful
                    var api_key = client.apiKey;
                    console.log("Authentication successful !", api_key);
                }
            });
            console.log('second method completed');
            resolve({newData: api_key});
        }, 2000);
    });
    return promise;
};

第三个函数

这个函数我想访问函数一和函数二中的变量。我已经包含了一个控制台日志，以便我可以看到控制台上打印的变量。

我还想访问这些函数以在第三个函数/方法中使用。

  var thirdMethod= function() {
    var promise = new Promise(function(resolve, reject){
 console.log('show both functions', emailUser, api_key);
        }, 3000);
    });
    return promise;
};

    firstMethod()
        .then(secondMethod)
        .then(thirdMethod);

Answer 1

当 API 调用得到响应时，您需要在函数体内进行解析。

var firstMethod = function() {
    var promise = new Promise(function(resolve, reject){
        setTimeout(function() {
            app.post('/api/data', function (req, res) {
                console.log(req.body);
                var emailUser = req.body.email;                            
                res.send(emailUser);

                //resolve when get the response
                resolve({data: emailUser });
            });

        }, 2000);
    });
    return promise;
};

<小时/>

出现错误时您必须需要解决或拒绝。这里我解决了错误并将 api_key 设置为 empty。

var secondMethod = function(someStuff) {
    var promise = new Promise(function(resolve, reject){
        setTimeout(function() {
            nodePardot.PardotAPI({
                userKey: 34535345,
                email: fsf@dd.com,
                password: fd3sv34f,
                DEBUG: true
            }, function (err, client) {
                if (err) {
                    // Authentication failed
                    console.error("Authentication Failed", err);
                    resolve({newData: ''});

                } else {
                    // Authentication successful
                    var api_key = client.apiKey;

                    console.log("Authentication successful !", api_key);
                    resolve({newData: api_key});
                }
            });

        }, 2000);
    });
    return promise;
};

<小时/>

function thirdMethod(result) {
  console.log('show both functions', result[0].data, result[1].newData);
};

Promise.all([firstMethod(), secondMethod()])
.then(thirdMethod);

<小时/>

供引用

var firstMethod = function() {
    var promise = new Promise(function(resolve, reject) {
        setTimeout(function() {

            //resolve when get the response
            resolve({
                data: "a"
            });
        });

    }, 2000);

    return promise;
};

var secondMethod = function() {
    var promise = new Promise(function(resolve, reject) {
        setTimeout(function() {

            //resolve when get the response
            resolve({
                data: "b"
            });
        });

    }, 2000);

    return promise;
};

var thirdMethod = function(result) {
    console.log(result[0].data, result[1].data);
};

Promise.all([firstMethod(), secondMethod()]).then(thirdMethod);

输出:a b