What's the commonly accepted pattern for representing state in Node.js

Question

What's the commonly accepted pattern for representing state in Node.js

For example in classic object oriented programming I might have a class School which has an array of String representing students (not the ideal data structure but for illustration purposes only). It might look something like this

class School {
    String name;
    String[] students;
}

I could then instantiate a bunch of different schools each with a different name and different students. How does this concept translate across to Node.js? If I had a School module than a single instance is shared across the entire application. My initial thought is to represent each school as JSON object and basically pass around JSON where I would normally be passing around an instance of School. Is this the right idea and are there alternative approaches?

javascript
node.js
functional-programming

Answer 1

If the state should be hidden from the outside (i.e. protected attributes) you could do something like this:

SchoolFactory = {
    create: function(name, students) {
        students = students || [];
        // return the accessor methods
        return {
            getName: function() {
                return name;
            },
            addStudent: function(student) {
                students.push(student);
            }
            // add more methods if you need to
        }
    }
}

var school = SchoolFactory.create('Hogwarts');
console.log(school); // will not display the name or students
school.addStudent('Harry');

Answer 2

constructors and instances:

function School(name, students) {
  this.name = name;
  this.students = students || [];
};
School.prototype.enroll = function (student) {
  if (!~this.students.indexOf(student)) {
    this.students.push(student);
  } else {
    throw new Error("Student '" + student + "' already enrolled in " + this.name);
  }
};
var s = new School("Lakewood");
console.log(s.name);
console.log(s.students);
s.enroll("Me");
console.log(s.students);

Answer 3

I don't about any patterns...but if you like the modules...you can declare a school module and have a School class in it's export. Single instance won't be shared, since you'll be instantiating the class