DHBW Mobile Web Dev - Practice Student Array Readline

readline_students.js

//import from node.js core to read from stdin
var readline = require('readline');

//Configure Readline
var rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

//Init Array for Students
var studentArray = [];

//Student Model as Module
var Student = require('./student.js');

//Just a Welcome Message...
console.log("Hello, my name is Siri. I will assist you to add students");

/**
 * Ask two questions via readline, print resulting array and restart again by calling itself
 * two readlines are nested, because they are async.
 */
var askUser = function () {
    console.log("We will create new Student. Please answer two questions. Or just type 'exit'");

    rl.question("Enter Firstname: ", function(answer) {
        if (checkExit(answer)) {
            return;
        }

        var newStudent = new Student(); //no params, means they get value undefined
        newStudent.first = answer;

        rl.question("Enter Lastname: ", function(answer) {
            if (checkExit(answer)) {
                return;
            }

            newStudent.last = answer;

            studentArray.push(newStudent);

            //sort array
            // provide function 'studentCompare' which can compare student objects
            // refer to @ https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort
            studentArray.sort(studentCompare)

            //Print out
            printArray();
            //And restart
            askUser();
        });
    });
};



/**
 * Compare two objects by string compare of its property 'last'
 * which should be the lastName in this context.
 * @param a
 * @param b
 * @returns {number}
 */
var studentCompare = function (a, b) {
    //a is less than b by some ordering criterion
    if (a.last < b.last) {
        return -1;
    }
    //a is greater than b by the ordering criterion
    if (a.last > b.last) {
        return 1;
    }
    // a must be equal to b
    return 0;
}

/**
 * check if answer parameter === 'exit' then exit readline
 * @param answer
 * @returns {boolean}
 */
var checkExit = function(answer) {
    if (answer === "exit" || answer === "quit") {
        console.log("Goodbye. See you next time...");
        rl.close();
        return true;
    }

    return false;
};

/**
 * print contents of Array 'studentArray' to Console
 */
var printArray = function () {
    var str = '[';
    for (var index in studentArray) {
        if (index > 0) {
            str += ", "
        }
        var curStudent = studentArray[index];
        str += curStudent.print();
    }
    str += ']';
    console.log(str);
};

//Start asking
askUser();

student.js

//Constructor
// will be called with 'new'
var Student = function(first, last, mail) {
    this.first = first;
    this.last = last;
    this.mail = mail;
};

//Prototype
Student.prototype = {
    print: function() {
        return (this.first + " " + this.last);
    },
    print2: function() {
        return (this.last + ", " + this.first);
    }
};

module.exports = Student;