The ultimate guide to coding interviews: Learn and practice JavaScript design patterns tested by FAANG engineers. Get interview-ready in just a few hours with battle-tested solutions.

If you're an experienced developer, chances are your interviewer won't ask you about language syntax. Instead, they'll focus on things that test your understanding of software architecture, and how capable you are at finding optimized solutions to given problems. 

That’s where a strong understanding of design patterns comes in handy. It's often useful to be able to draw on established patterns instead of reinventing the wheel.

In this course, you will learn how to effectively deploy design patterns to answer interview questions. The course is divided into four sections: Creational Patterns, Structural Patterns, Behavioral Patterns, and Architectural Patterns. Each section has its own set of design patterns which you’ll learn to use through various challenges. 

Every challenge contains a detailed solution explanation. By the end of this course (and with some practice), you will be able to confidently use design patterns to tackle advanced coding interview questions in JavaScript.

JavaScript Design Patterns for Coding Interviews

# Problem statement 

In this challenge, you have the abstract constructor function `Loans`. There are **three** types of loans that can be given:

* `HomeLoan`

* `StudentLoan`

* `PersonalLoan`


You need to implement `Loans` such that it decides which loan instance to instantiate, given the input parameters. Implement a function `getloan` for this purpose. `getloan` should take the following parameters:

* `type`: type of loan

* `amount`: amount of the loan

*  `duration`: duration of the loan



All the three loans mentioned above have the following properties:

* `amount`: the amount of loan required (in dollars)

* `duration`: the duration of time  (in years) for which the loan is borrowed

* `interest`: the annual interest rate

The `interest` is different but fixed for all three loans:

* The `interest` on `HomeLoan` is: `0.08`

* The `interest` on `StudentLoan` is: `0.03`

* The `interest` on `PersonalLoan` is: `0.05`


Also defined for these loans is the `calculateInterest` method that calculates the simple interest on the `amount` borrowed for the given `duration`. Use the following formula to calculate the total interest:

>$Total Interest = amount * interest * duration$ 



In this challenge, you have to implement the abstract pattern to solve the given problem.

Before We Begin

Introduction To Design Patterns

Creational Patterns

Structural Patterns

Behavioral Patterns

Architectural Patterns

Conclusion

Challenge: Abstract Pattern

Problem statement