ES5 Object-Oriented Programming

// OOP encapsulation
function Student(props){ // Constructor (properties are defined inside the constructor. Follows the convention of capitalizing the first letter)
  this.name = props.name || 'Anonymous';  // Default 'Anonymous'
  this.grade = props.grade || 1;
}
Student.prototype.hello = function(){ // Define methods on the constructor's prototype
  console.log('Hello, ' + this.name + ', you are in grade ' + this.grade);
}


// Usage
function createStudent(props) { // A wrapper for new constructor, with two benefits: 1) no need to use new, 2) flexible parameters
    return new Student(props || {}) // Create an instance via new constructor and pass in parameters/properties
}

var niming = createStudent();
niming.hello();

var xiaoming = createStudent({
  name:'Xiaoming',
  grade:2
});
xiaoming.hello();


// Inheritance
function inherits(Child, Parent) { // Inheritance wrapper method: inherits(ChildClass, ParentClass)
    var F = function () {}; // Define an empty function F
    F.prototype = Parent.prototype; // Point F's prototype to the parent's prototype
    Child.prototype = new F(); // Point the child's prototype to new F()
    Child.prototype.constructor = Child; // Fix the constructor on the child's prototype to point to the child class itself
}

function PrimaryStudent(props) { // Define the child class constructor
    Student.call(this, props); // Fix the this reference
    this.age = props.age || 8; // Add a new child class property
}

inherits(PrimaryStudent, Student); // Call the inheritance wrapper to implement inheritance

PrimaryStudent.prototype.getAge = function(){ // Add a method to the child class
  console.log(this.name + ', you are ' + this.age + ' years old');
}


// Using the inherited class
function createPrimaryStudent(props) { // A wrapper for new constructor, with two benefits: 1) no need to use new, 2) flexible parameters
    return new PrimaryStudent(props || {}) // Create an instance via new constructor and pass in parameters/properties
}

var xiaohong = createPrimaryStudent({
  name:'Xiaohong',
  grade:3,
  age:10
});
xiaohong.hello();
xiaohong.getAge();