Javascript object prototype function

Question

I have three methods in an object.

2 of them work properly, when third is printed - it prints out the code itself, not function. Here is the code and how it looks in console:

function Students(name, lastname, grades){
 this.name = name;
 this.lastname = lastname;
 this.grades = grades;
 this.addGrade = function(a){
 this.grades.push(a);
 }
 this.printData = function(){
 console.log("Name: " + this.name);
 console.log("Grades: " + this.grades);
 console.log("Average: " + this.gradeAvg);
 }
 this.gradeAvg = function(){
 console.log("blabla");
 }
}
var StudentasA = new Students("Petras", "Petrauskas", [8, 9, 9, 8, 7]);
var StudentasB = new Students("Jurgis", "Jurgauskas", [6, 7, 5, 4, 9]);
StudentasA.printData();
StudentasA.addGrade(28);
StudentasA.printData();

console:

console view

• SLaks: You aren't actually using a prototype.

Answer 1

You need to call the function

this.gradeAvg()
// ^^

function Students(name, lastname, grades){
 this.name = name;
 this.lastname = lastname;
 this.grades = grades;
 this.addGrade = function(a){
 this.grades.push(a);
 }
 this.printData = function(){
 console.log("Name: " + this.name);
 console.log("Grades: " + this.grades);
 console.log("Average: " + this.gradeAvg());
 // ^^
 }
 this.gradeAvg = function(){
 return this.grades.reduce(function (a, b) { return a + b; }) / this.grades.length;
 }
}
var StudentasA = new Students("Petras", "Petrauskas", [8, 9, 9, 8, 7]);
var StudentasB = new Students("Jurgis", "Jurgauskas", [6, 7, 5, 4, 9]);
StudentasA.printData();
StudentasA.addGrade(28);
StudentasA.printData();

Answer 2

Your code never actually calls the function.

Instead, you concatenate the function itself directly into the string.

You want parentheses.