Questions

1 of 17

1Explain the concept of 'callback hell' and how to mitigate it.

2What is a Promise in JavaScript?

3Explain the three states of a Promise.

4How do you create a new Promise in JavaScript?

5What is the purpose of `Promise.resolve()` and `Promise.reject()`?

6How do you handle the result of a Promise?

7What is Promise chaining?

8How do you handle errors in a chain of Promises?

9What is the purpose of `Promise.all()`, `Promise.race()`, `Promise.any()`, `Promise.allSettled()`?

10How can you handle multiple Promises concurrently without using `Promise.all()`?

11What is the purpose of the `async` and `await` keyword in JavaScript??

12How do you handle errors when using `async/await`?

13Do all `async` functions return Promises? Why or why not?

14How does `Promise.finally()` work?

15How do you convert a callback-based function into a Promise-based function?

16What is the purpose of `Promise.promisify()`?

17How can you create a custom Promise with timeout functionality?

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Explain the concept of 'callback hell' and how to mitigate it.

Callback hell (also called the "Pyramid of Doom") occurs when multiple and deeply nested callbacks are used producing difficult-to-read deeply indented, unmaintainable code.

This is a common issue when dealing with asynchronous operations. To make code more organised and readable, you can use techniques like

1
named functions
2
modularisation
3
Promises
4
async/await to