Javascript Node.js获取函数的返回值

我刚开始研究node.js并开始了解它的概念，我在理解回调时遇到了一点困难，我试图做的是调用函数getUserBranch（），在函数getOffers（）中

我了解到，由于node.js的异步特性，在完成执行后，最好使用回调函数来获取所需的数据

现在，我在检索getUserBranch返回的值时遇到了问题，我不知道如何执行，回调函数具有该值，但如何从中获取该值

file2.js

file1.js

---

在异步调用中，使用堆栈中的回调函数。看看这个：

var getUserBranch = function(email,callback) {
    client.execute('SELECT * from branch WHERE email=?', [ email ], function(err, data, fields) {
        if (err)
            console.log("error");
        else{
            console.log('The solution is in branch: \n', data);
            /* This data stack 3  */
            callback(data.rows[0];);
        }
    });
};

var getOffers = function (email, callback) {
    var branchObj = require('./file2.js');
    branchObj.getUserBranch(email, function(data){
        /* This data stack 2  */
        callback(data);
    });
};

function anyFunction(){
    getOffers("xx@xxx.com", function(data){
        /* This data stack 1  */
        console.log(data);
    });
}

var getOffers = function (email) {

   var branchObj = require('./file2.js');
   var branchList = branchObj.getUserBranch(email,getList));
   return branchList;
};

var getList = function(res){
  var results=res;
  return results;
}

var getUserBranch = function(email,callback) {
    client.execute('SELECT * from branch WHERE email=?', [ email ], function(err, data, fields) {
        if (err)
            console.log("error");
        else{
            console.log('The solution is in branch: \n', data);
            /* This data stack 3  */
            callback(data.rows[0];);
        }
    });
};

var getOffers = function (email, callback) {
    var branchObj = require('./file2.js');
    branchObj.getUserBranch(email, function(data){
        /* This data stack 2  */
        callback(data);
    });
};

function anyFunction(){
    getOffers("xx@xxx.com", function(data){
        /* This data stack 1  */
        console.log(data);
    });
}