minamonsi / javascript-foundations

JavaScript-Foundations

The module challenge is the afternoon project or assignment that students work through independently. This expands on the guided project completed earlier with the instructor.

Advanced CSS and JavaScript

JavaScript Foundations

Objectives

• use let, const, var and demonstrate their differences.
• understand and be able to use different operators.
• write a basic for loop / while loop.
• write control flow using if/else statements.
• use function declarations, expressions, and arrow functions and describe their differences

Introduction

Today you'll build a mortgage rate calculator that runs in the console. As you learned today, JavaScript is great for adding functionality and interactivity to a webpage. In our exercises today we won't be working with the visual part of the webpage, but the work you do here could be combined with HTML and CSS to create a fully functioning single page application.

The formula for a monthly mortgage payment is as follows:

Or, in plain text:

M = P [ I ( 1 + I )^N ] / [ ( 1 + I )^N – 1 ]

In order to find your monthly payment amount "M,” you need to plug in the following three numbers from your loan:

P = Principal amount (the total amount borrowed) I = Interest rate on the mortgage N = Number of periods (monthly mortgage payments)

Exercises outlined in the index.js file walk you through a series of steps for building a robust and functional mortgage calculator.

Check out the resources below for more of a step-by-step walk-through of this math, and to see a well-designed mortgage calculator web app. Believe it or not, the backend you write today could power a beautiful site like that!

Instructions

Task 1: Set up Project

Using VSCode and Command Line:

1. Fork repo and add TL as collaborator on Github.
2. Clone your fork (not Lambda's repo by mistake!).
3. cd into your newly cloned repository.
4. Create a new branch by typing git checkout -b <firstName-lastName>.

Task 2: Complete MVP Requirements

Find the index.js file and complete the tasks as written. Your final product should be a function called variableInterestRate that accepts a principal, interest rate, mortgage length, and credit score and returns 10 different options of monthly payments.

As you work on your code you should make use of console.log to check your progress and debug.

Task 2b: Exit Ticket

Once you begin, you will have 15 minutes to answer the questions here

The completion of these questions is mandatory for MVP. However, passing the quiz doesn't affect your standing as a Lambda School student whatsoever. This is Lambda School testing itself! Please answer honestly and to the best of your ability without using external references.

Task 3: Stretch Goals

After you have completed the requirements, try any of the following challenges. As always, note that these may require additional research beyond what you learned in this module.

• Add Property Tax, Homeowner's insurance and HOA fees as parameters in your function to calculate total monthly spending on housing
• Build a calculator function that accepts monthly payment and interest rate and returns the maximum loan that a person could afford
• Explore using window.prompt() to allow a user to input parameters in the browser
• Refactor your variableInterestRate() function to accept an array of interest rates (make sure to copy and paste as to not lose your work!)

Submission format

Follow these steps for completing your project.

1. Submit a pull request to merge <firstName-lastName> branch into master. Please don't merge your own pull request
2. Add your TL as a reviewer on the pull-request
3. Your TL will count the project as complete by merging the branch back into master

Resources

🧮 Detailed Walk-through of Mortgage Calculations

👀 Mortgage Calculator Web App for Inspiration

🤟 window.prompt for Stretch Goals