JavaScript Mastery from Zero to Hero - Prepare for Coding Interviews - What Are Callback Functions in JavaScript

The video tutorial introduces the concept of callback functions, explaining that they are functions passed as arguments to other functions and invoked within them. An example is provided using a sign-in function, where a callback function logs a message when a user signs in. The tutorial walks through the implementation, demonstrating how the callback function is used to dynamically handle user input and log the sign-in message. The video concludes with a review of the process, emphasizing the importance of understanding callback functions for dynamic programming tasks.

What is a callback function?

• A function that returns another function.

• A function that is executed immediately after its definition.

• A function that calls itself recursively.

• A function passed as an argument to another function.

In the context of the lesson, what is the purpose of a callback function?

• To execute a function immediately.

• To handle errors in a program.

• To pass a function as an argument to be called later.

• To create a new function from existing ones.

What does the 'sign in' function do in the example?

• It prompts the user to enter their password.

• It logs a user out of the system.

• It logs a message indicating a user has signed in.

• It creates a new user account.

How does the 'sign user in' function utilize the callback?

• It calls the callback function immediately without any arguments.

• It uses the callback to log the user out.

• It passes the user's name to the callback function.

• It ignores the callback function entirely.

What happens when you remove and re-add the parenthesis in the example?

• The function stops working.

• The sign-in message changes.

• The user is prompted to sign in again.

• The callback function is deleted.

Why is the 'sign user in' function commented out at the end?

• To prevent the program from crashing.

• To save memory space.

• To stop the user from being prompted repeatedly.

• To allow the user to sign out.

What is the main takeaway from the sign-in example?

• Callback functions are only used for user authentication.

• Callback functions can be used to execute code dynamically.

• Callback functions are not useful in real-world applications.

• Callback functions are only for logging purposes.