Stack overflow concept in Javascript - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this recursive function?

Consider this JavaScript function that calls itself recursively without a proper stop condition. What will happen when we run countdown(5)?

Javascript

function countdown(n) {
  console.log(n);
  countdown(n - 1);
}
countdown(5);

A Prints 5 once and stops

B Prints numbers 5 to 1 then stops

C Prints numbers 5 to 0 then stops

D Throws a RangeError: Maximum call stack size exceeded

💡 Hint

Think about what happens when the function never stops calling itself.

The function calls itself with decreasing numbers but never stops. Eventually, JavaScript runs out of space to keep track of calls and throws a RangeError due to stack overflow.

🧠 Conceptual

intermediate

What causes a stack overflow in JavaScript?

Which of the following best describes what causes a stack overflow error in JavaScript?

A Calling functions recursively without a base case

B Using asynchronous functions incorrectly

C Using too many global variables

D Declaring too many variables inside a function

💡 Hint

Think about what happens when functions keep calling themselves endlessly.

A stack overflow happens when the call stack grows too large, usually because functions call themselves without stopping, exhausting memory reserved for calls.

❓ Predict Output

advanced

What is the output of this recursive factorial function?

Look at this factorial function. What will factorial(5) return?

Javascript

function factorial(n) {
  if (n === 0) return 1;
  return n * factorial(n - 1);
}
console.log(factorial(5));

A Throws RangeError: Maximum call stack size exceeded

B 24

C 120

D Undefined

💡 Hint

Factorial of 5 is 5 * 4 * 3 * 2 * 1.

The function correctly uses a base case (n === 0) to stop recursion. It calculates 5! = 120.

❓ Predict Output

advanced

What error does this code produce?

This function calls itself without a base case. What error will appear when running infinite()?

Javascript

function infinite() {
  return infinite();
}
infinite();

A RangeError: Maximum call stack size exceeded

B TypeError: infinite is not a function

C SyntaxError: Unexpected token

D No error, runs forever

💡 Hint

Think about what happens when a function calls itself endlessly without stopping.

The function calls itself endlessly without a base case, causing the call stack to overflow and throw a RangeError.

🧠 Conceptual

expert

How can you prevent stack overflow in recursive functions?

Which of these is the best way to avoid stack overflow errors in recursive JavaScript functions?

A Avoid using recursion and only use loops

B Use a base case to stop recursion and avoid infinite calls

C Use global variables to store intermediate results

D Declare all variables outside the function

💡 Hint

Think about what stops a recursive function from calling itself forever.

A base case is a condition that stops recursion. Without it, the function calls itself endlessly, causing stack overflow.