Why functions are needed in Javascript - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of repeated code without functions

What is the output of this JavaScript code that repeats similar logic without using functions?

Javascript

console.log(5 + 3);
console.log(10 + 2);
console.log(7 + 8);

A 8 12 15

B 15\n12\n8

C 8\n12\n15

D Error

💡 Hint

Look at each console.log output separately.

Each console.log prints the sum of two numbers. They print 8, then 12, then 15 on separate lines.

🧠 Conceptual

intermediate

Why use functions instead of repeating code?

Why do programmers use functions instead of writing the same code multiple times?

A To make code shorter and easier to reuse

B To make code run slower

C To confuse other programmers

D To increase the number of lines in the program

💡 Hint

Think about saving time and effort.

Functions help avoid repeating code, making programs shorter and easier to maintain.

❓ Predict Output

advanced

Output of function usage for repeated addition

What is the output of this code that uses a function to add two numbers?

Javascript

function add(a, b) {
  return a + b;
}
console.log(add(5, 3));
console.log(add(10, 2));
console.log(add(7, 8));

A Error

B undefined\nundefined\nundefined

C 15\n12\n8

D 8\n12\n15

💡 Hint

The function returns the sum of two numbers.

The function add returns the sum of its two arguments, so the console logs print 8, 12, and 15.

🧠 Conceptual

advanced

Main benefit of functions in large programs

What is the main benefit of using functions in large programs?

A They help organize code into smaller, manageable parts

B They make programs run without errors automatically

C They increase the program size to use more memory

D They prevent the program from running too fast

💡 Hint

Think about how to handle complexity.

Functions break big programs into smaller parts, making them easier to understand and fix.

❓ Predict Output

expert

Output of function with side effect and return

What is the output of this code that uses a function to print and return a value?

Javascript

function greet(name) {
  console.log('Hello, ' + name + '!');
  return name.length;
}
const length = greet('Alice');
console.log(length);

A Error

B Hello, Alice!\n5

C Hello, Alice!\nundefined

D 5\nHello, Alice!

💡 Hint

The function prints a greeting and returns the length of the name.

The function first prints 'Hello, Alice!' then returns 5, which is printed next.