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Asynchronous JavaScript
Question 1
What is the purpose of the setTimeout function?
- A
Executes a function repeatedly at fixed intervals
- B
Executes a function once after a delay
- C
Executes a function immediately
- D
Cancels a delayed function
Question 2
What does the then() method of a Promise do?
- A
Handles rejected promises
- B
Cancels an unresolved promise
- C
Converts a callback to a promise
- D
Handles fulfilled promises
Question 3
Which method allows handling errors in promises?
- A
catch()
- B
then()
- C
resolve()
- D
finally()
Question 4
What does async do when used with a function?
- A
Makes the function synchronous
- B
Automatically wraps the function's return value in a promise
- C
Stops the execution of the function
- D
Immediately executes the function
Question 5
What is the purpose of the await keyword?
- A
Delays code execution indefinitely
- B
Converts a promise into a callback
- C
Pauses execution of an async function until a promise resolves
- D
Handles rejected promises
Question 6
What is the difference between setTimeout and setInterval?
- A
setTimeout runs once, while setInterval executes repeatedly at intervals
- B
setTimeout executes repeatedly, while setInterval runs once
- C
Both execute functions immediately
- D
Both are used for canceling asynchronous tasks
Question 7
What is the event loop's role in JavaScript?
- A
To execute synchronous code
- B
To prioritize promises over callbacks
- C
To manage and execute asynchronous operations in the call stack
- D
To handle HTTP requests
Question 8
Which queue has a higher priority in the JavaScript event loop?
- A
Callback queue
- B
Timer queue
- C
Render queue
- D
Microtask queue
Question 9
What is the output of the following code?
console.log("A");
setTimeout(() =>
console.log("B"), 0);
Promise.resolve().then(() =>
console.log("C"));
console.log("D");
- A
A, B, C, D
- B
A, D, B, C
- C
A, D, C, B
- D
B, C, A, D
Question 10
What is the purpose of Promise.finally()?
- A
Executes only when a promise is fulfilled
- B
Executes only when a promise is rejected
- C
Cancels unresolved promises
- D
Executes after a promise is settled, regardless of its state
There are 10 questions to complete.
