The Modern JavaScript Bootcamp (2019) - Closures

The video tutorial explores JavaScript closures, explaining their relation to functions and function scope. It begins with a basic example to illustrate closure fundamentals, then delves into more advanced concepts, including practical applications like creating private variables and currying. The tutorial emphasizes the importance of closures in asynchronous programming and provides exercises to reinforce learning.

What is a closure in JavaScript?

• A function without any parameters

• A function bundled with its lexical environment

• A variable that cannot be changed

• A method to handle asynchronous operations

In the context of closures, what does the term 'lexical scope' refer to?

• The global scope of a program

• The scope where a function is defined

• The scope where a function is executed

• The scope of a function's parameters

How do closures enable asynchronous programming in JavaScript?

• By making functions execute faster

• By allowing functions to access variables from their defining scope

• By preventing functions from accessing global variables

• By ensuring functions run in parallel

What is the purpose of using closures to create private variables?

• To make variables immutable

• To enhance the performance of a program

• To allow variables to be accessed globally

• To restrict variable access to specific functions

In the createCounter example, what does the 'increment' method do?

• Resets the count to zero

• Increases the count by one

• Returns the current count

• Decreases the count by one

What is currying in the context of JavaScript functions?

• Transforming a function to take multiple arguments

• Transforming a function to take one argument at a time

• Creating a function without parameters

• Executing a function immediately

How does the 'createAdder' function utilize closures?

• By returning a function that adds a fixed number to its argument

• By creating a global variable accessible to all functions

• By preventing any changes to its parameters

• By executing a function immediately

What is the main advantage of using closures in JavaScript?

• They make code run faster

• They allow functions to remember the environment in which they were created

• They prevent any errors in the code

• They make functions easier to read

In the 'createTipper' function, what does the inner function do?

• Calculates the total bill amount

• Returns the tip amount based on the bill

• Prints the bill amount

• Saves the tip percentage

Why is understanding closures important for asynchronous programming?

• They prevent functions from accessing global variables

• They enable functions to access variables from their defining scope even after execution

• They allow functions to execute faster

• They ensure functions run in a specific order