Unit 8 – Temperature & Circle Area

🧠 JavaScript Crash Course

Before starting this project, review a few key JavaScript basics.

var vs let

Keyword	Scope	Redeclaration	Typical Use
var	Function-scoped	Can be redeclared	Legacy code (older JavaScript)
let	Block-scoped	Cannot be redeclared in same block	Modern variable declaration

Example:

let x = 10;
x = x + 5;   // ✅ works
let x = 7;   // ❌ error: already declared

Quick Tip: Always use let for variables that change, and const for values that don’t.

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Simple Math in JavaScript

You can use math operators the same way you would on a calculator:

Operator	Meaning	Example	Result
+	Addition	5 + 3	8
-	Subtraction	9 - 2	7
*	Multiplication	4 * 2	8
/	Division	9 / 3	3
**	Exponent	2 ** 3	8
%	Remainder	10 % 3	1

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💡 Project Overview

You’ll build a simple JavaScript page that uses prompt() and alert() for user input and output.
Students will complete two shell functions:

1. convertTemp() — Converts Fahrenheit to Celsius
2. circleArea() — Calculates the area of a circle

Each function is triggered by a button on the web page.

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🧩 What to Build

You have two buttons in index.html that call functions in script.js:

Buttons

• “Convert Temperature” → convertTemp()
• “Calculate Circle Area” → circleArea()

Functions to Implement

function convertTemp() {
  // Prompt: "Enter temperature in Fahrenheit"
  // Convert to Celsius: (fahrenheit - 32) * 5 / 9
  // Alert: "Temperature in Celsius: <value>" (2 decimals)
}

function circleArea() {
  // Prompt: "Enter circle radius"
  // Compute area: Math.PI * radius * radius
  // Alert: "Area of the circle: <value>" (2 decimals)
}

⚙️ Required Prompt & Alert Text (exact!)

Function	Prompt Text	Alert Text
convertTemp()	Enter temperature in Fahrenheit	Temperature in Celsius: <value>
circleArea()	Enter circle radius	Area of the circle: <value>

The autograder checks for exact string matches.
Even capitalization matters!

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🧱 File Structure

├── index.html
├── script.js
└── .github/
    └── workflows/
        └── classroom.yml

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🧪 Autograding (GitHub Classroom)

The tests run automatically via GitHub Actions each time you push your code.

• ✅ Test 1 (50 pts):
  convertTemp()

  • Input: 212
  • Expected output: Temperature in Celsius: 100.00
  • Checks exact prompt text

• ✅ Test 2 (50 pts):
  circleArea()

  • Input: 5
  • Expected output: Area of the circle: 78.54
  • Checks exact prompt text

⚙️ Behind the Scenes

The workflow file in .github/workflows/classroom.yml:

• Creates the test configuration dynamically
• Runs Node to simulate prompt() and alert() in your script
• Reports your score directly to GitHub Classroom

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🚀 How to Run Locally

1. Open index.html in your browser.
2. Click “Convert Temperature” or “Calculate Circle Area”.
3. Follow the prompt()s that appear and verify the results in alert() pop-ups.

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✅ Tips for Success

• Use parseFloat() to convert text input to numbers.
• Use .toFixed(2) to format decimals properly.
• Always use the exact prompt/alert wording shown above.
• Don’t use console.log() — this project only uses prompt() and alert().

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🎯 Example Output

Example 1

Prompt: Enter temperature in Fahrenheit
User enters: 212
Alert: Temperature in Celsius: 100.00

Example 2

Prompt: Enter circle radius
User enters: 5
Alert: Area of the circle: 78.54

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🏁 Goal

When you push your completed script.js, GitHub Classroom will automatically:

1. Run both tests
2. Award up to 100 points
3. Sync your results back to your assignment page