3.12 Calling Procedures Homework in JavaScript

Complete the 4 tasks below as homework:

  1. Create the functions
  2. Run the Code cell
  3. Have fun!

Hack — Example 1: Simple function with no parameters

%%js
// TODO: Call sayHello to print "Hello there!"
function sayHello() {
    console.log("Hello there!")
    
}
// sayHello();
sayHello();

<IPython.core.display.Javascript object>
  • Does the code run as expected?
  • If yes, move on to the next hack.

Hack — Example 2: Function with one parameter

%%js
// TODO: Call greet with your name to welcome the student
function greet(name) {
    console.log("Hello," + name + "!"); 

    
}
greet("David", "B");

<IPython.core.display.Javascript object>
  • Does your code properly greet the person?
  • Are there no errors in your code?
  • If yes, move on to the next hack.

Hack — Example 3: Function with two parameters

%%js
// Function to add two numbers
function addNumbers(a, b) {
    return a + b;
}

// Call the function with two numbers and print the result
console.log(addNumbers(3, 7));  // 10

<IPython.core.display.Javascript object>
  • Does addNumbers(3, 7) give 10?
  • Does it work for other numbers too?
  • If yes, move on to the next hack.

Hack — Example 4: Function that returns a value

%%js
// Implement factorial(n) to return n!
function factorial(n) {
    if (n === 0 || n === 1) {
        return 1;  // base case
    } else {
        return n * factorial(n - 1);  // recursive call
    }
}

// Example: factorial(5) should return 120
result = factorial(5);
console.log(result);  // 120

// Example: factorial(0) should return 1
result = factorial(0);
console.log(result);  // 1

// Example: factorial(1) should return 1
result = factorial(1);
console.log(result);  // 1


<IPython.core.display.Javascript object>
  • Does factorial(0) return 1?
  • Does factorial(1) return 1?
  • Does factorial(5) return 120?
  • If yes, move on to the next hack.

Hack - Challenge Example 5: Function calling another function

%%js
// Dictionary (object) of items and their prices
const storeItems = {
  apple: 2.0,
  banana: 1.5,
  milk: 3.25,
  bread: 2.0
};

// Function 1: calculate subtotal
function getSubtotal(cart) {
  let subtotal = 0;
  for (let item in cart) {
    if (storeItems[item]) {          
      subtotal += storeItems[item] * cart[item];  
    }
  }
  return subtotal;
}

// Function 2: add tax
function addTax(subtotal, taxRate) {
  return subtotal * (1 + taxRate);
}

// Function 3: checkout
function checkout(cart, taxRate) {
  const subtotal = getSubtotal(cart);
  const total = addTax(subtotal, taxRate);
  console.log(`Subtotal: $${subtotal.toFixed(2)}`);
  console.log(`Total (with tax): $${total.toFixed(2)}`);
}

// Example cart for testing
const myCart = {
  apple: 2,
  milk: 1,
  bread: 1
};

// Call checkout with 8% tax
checkout(myCart, 0.08);

<IPython.core.display.Javascript object>
  • If the shopping cart contains 2 apples, 1 milk, and 1 bread, will your program show a subtotal of $8.00 and a total of $8.64 with an 8% tax rate?
  • Try changing the cart to 3 bananas and 2 milk — should the subtotal be $10.25 and the total with 8% tax be $11.07?
  • If your output matches these totals, your function calls and calculations are correct!