Foundations - Practice Exercises

Topic: Foundations
Concepts: Variables, data types, console, operators

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📝 Multiple Choice Questions

Question 1

Which of the following is the correct way to declare a variable that can be reassigned?

• A) const name = "John";
• B) let name = "John";
• C) var name = "John";
• D) Both B and C

Question 2

What will console.log(typeof null) output?

• A) “null”
• B) “undefined”
• C) “object”
• D) “boolean”

Question 3

Which of these is NOT a valid variable name in JavaScript?

• A) firstName
• B) $price
• C) 2ndPlace
• D) _secret

Question 4

What does console.log(5 + "3") output?

• A) 8
• B) “53”
• C) 53
• D) Error

Question 5

Which data type is NaN (Not a Number)?

• A) string
• B) number
• C) undefined
• D) object

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💻 Practical Coding Exercises

Exercise 1: Variable Practice

Create variables for a person’s information and display them:

// TODO: Create variables for:
// - firstName (string)
// - lastName (string)
// - age (number)
// - isStudent (boolean)
// - favoriteColor (string)

// TODO: Use console.log to display all information
// Expected output format: "John Doe, age 25, student: true, favorite color: blue"

Exercise 2: Calculator

Create a simple calculator using basic operators:

// TODO: Create two variables with numbers
// TODO: Calculate and log the following:
// - Sum
// - Difference
// - Product
// - Division
// - Remainder (modulus)
// - Exponentiation

Exercise 3: Data Type Explorer

Create variables of different types and explore them:

// TODO: Create one variable of each type:
// - string, number, boolean, null, undefined

// TODO: Use typeof to check each variable's type
// TODO: Try some operations and see what happens

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🎯 Challenge Problems

Challenge 1: Temperature Converter

Create a program that converts temperatures between Celsius and Fahrenheit:

// TODO: Create variables for temperature conversion
// Formula: F = (C × 9/5) + 32
// Formula: C = (F - 32) × 5/9

// Test with: 0°C should be 32°F, 100°C should be 212°F

Challenge 2: Age Calculator

Calculate someone’s age in different units:

// TODO: Given a birth year, calculate:
// - Age in years
// - Age in months (approximate)
// - Age in days (approximate)
// - Age in hours (approximate)

const birthYear = 1995;
const currentYear = new Date().getFullYear();

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🔍 Debugging Exercises

Find and fix the errors in these code snippets:

Debug 1:

// What's wrong with this code?
const userName = "Alice";
let userAge = 25;
const userLocation = "New York";

console.log(
  "User: " + userName + ", Age: " + userAge + ", Location: " + userLocation,
);

userName = "Bob";

Debug 2:

// What's wrong with this code?
let price = 19.99;
let quantity = 3;
let total = price * quantity;

console.log("Total: $" + total.toFixed(2));

const 2ndPrice = 29.99;

Debug 3:

// What's wrong with this code?
let firstName = "John";
let lastName = "Doe";
let fullName = firstName + lastName; // Missing something?

console.log(fullName);

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📊 Self-Assessment Quiz

Rate your understanding (1-5 scale):

1. Variable Declaration: Can you correctly use let, const, and understand when to use each?
2. Data Types: Do you understand the 6 primitive types in JavaScript?
3. Operators: Can you use arithmetic, assignment, and other operators correctly?
4. Type Checking: Do you understand typeof and its quirks?
5. Console: Can you effectively use console.log() for debugging?

Goal: Aim for 4-5 in all areas before moving to the next topic.

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💡 Tips for Practice

1. Use Browser Console: Practice these exercises in your browser’s developer tools
2. Experiment: Try variations of the examples
3. Break Things: Intentionally make errors to see what happens
4. Ask Questions: If something doesn’t make sense, research or ask for help
5. Build Small Projects: Apply these concepts in mini-projects

Remember: Mastery comes from practice! 🚀