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JavaScript Design Patterns for Coding Interviews

Challenge: Solution Review

Explore how to implement the builder design pattern in JavaScript through a detailed solution review. Learn to structure classes and methods to create complex objects step-by-step, enhancing your understanding of creational patterns for coding interviews.

We'll cover the following...

Solution #

Node.js
function Assignment() {
  this.make = function(builder){
    builder.step1();
    builder.step2();
    builder.step3();
    builder.step4();
    return builder.get();
  }
}
 
function AssignmentBuilder(subject,level,dueDate) {
   this.assignment = null;
   this.step1 = function() {
        this.assignment= new Task();
    };
 
    this.step2 = function() {
        this.assignment.addSubject(subject);
    };
    this.step3 = function(){
      this.assignment.addLevel(level);
    }
    
    this.step4 = function(){
      this.assignment.addDuedate(dueDate);
    }
 
    this.get = function() {
        return this.assignment;
    };
}
 
function Task() {
    this.subject = null;
    this.level = null;
    this.dueDate = null; 
 
    this.addSubject = function(subject) {
        this.subject = subject;
    };
 
    this.addLevel = function(level) {
        this.level = level;
    };
    this.addDuedate = function(dueDate){
      this.dueDate = dueDate;
    }
    this.announcement = function(){
      console.log(`Your ${this.subject} assigment is: ${this.level}. It is due on ${this.dueDate}.`)
    }
}
 
var assignment = new Assignment();
var assignmentBuilder = new AssignmentBuilder("Math","Hard","12th June, 2020");
var mathAssignment = assignment.make(assignmentBuilder);
mathAssignment.announcement();

Explanation

You were given the following code:

var assignment = new Assignment();
var assignmentBuilder = new AssignmentBuilder("Math","Hard","12th June, 2020");
var mathAssignment = assignment.make(assignmentBuilder);
mathAssignment.announcement();

You had to complete the code implementation of this program. From the first line, we know that we need to have a class Assignment that accepts no parameters. So, let’s declare that first.

Node.js
function Assignment() {
}
var assignment = new Assignment();
var assignmentBuilder = new AssignmentBuilder("Math","Hard","12th June, 2020");
var mathAssignment = assignment.make(assignmentBuilder);
mathAssignment.announcement();

The code above gives an error since some other functions/methods being used are not defined. So, let’s move on to the next line.

var assignmentBuilder = new
...