Return values in Javascript - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this function call?

Consider the following JavaScript function. What will be logged to the console when foo() is called?

Javascript

function foo() {
  return 5 + 3;
}
console.log(foo());

A undefined

B 8

C NaN

D Error

💡 Hint

Remember that the return statement sends a value back to where the function was called.

The function foo returns the sum of 5 and 3, which is 8. The console.log prints this returned value.

❓ Predict Output

intermediate

What does this function return?

What is the value of result after calling bar()?

Javascript

function bar() {
  let x = 10;
  if (x > 5) {
    return x * 2;
  }
  return x / 2;
}
const result = bar();

A 10

B 5

C undefined

D 20

💡 Hint

Check the condition inside the function and which return statement runs first.

Since x is 10 which is greater than 5, the function returns 10 * 2 = 20 immediately.

❓ Predict Output

advanced

What is the output of this nested function call?

What will be printed when this code runs?

Javascript

function outer() {
  function inner() {
    return 'Hello';
  }
  return inner();
}
console.log(outer());

A Error

B undefined

C Hello

D outer

💡 Hint

The outer function calls the inner function and returns its result.

The inner function returns 'Hello', and outer returns the result of inner(), so console.log prints 'Hello'.

❓ Predict Output

advanced

What does this function return when no explicit return is given?

What is the output of this code?

Javascript

function noReturn() {
  let a = 5;
  let b = 10;
  let c = a + b;
}
console.log(noReturn());

A undefined

B Error

C NaN

D 15

💡 Hint

If a function does not return a value explicitly, what does it return by default?

Functions without a return statement return undefined by default in JavaScript.

❓ Predict Output

expert

What is the output of this asynchronous function?

What will be logged to the console when this code runs?

Javascript

async function asyncFunc() {
  return 'Done';
}
asyncFunc().then(console.log);

A Done

B Promise { 'Done' }

C undefined

D Error

💡 Hint

Remember that async functions return a Promise, but using .then() logs the resolved value.

The async function returns a Promise that resolves to 'Done'. The .then() logs the resolved value 'Done'.