Why promises are used in Javascript - Quick Recap

Recall & Review

beginner

What problem do promises solve in JavaScript?

Promises help manage asynchronous operations by avoiding callback hell and making code easier to read and maintain.

beginner

How do promises improve code readability?

Promises allow chaining with .then() and .catch(), which makes asynchronous code look more like synchronous code.

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What are the three states of a promise?

A promise can be pending (waiting), fulfilled (success), or rejected (error).

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Why is callback hell a problem?

Callback hell happens when callbacks are nested deeply, making code hard to read, debug, and maintain.

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How do promises handle errors better than callbacks?

Promises use .catch() to handle errors in one place, avoiding scattered error handling in nested callbacks.

What does a promise represent in JavaScript?

A A value that may be available now, later, or never

B A synchronous function

C A type of variable

D A way to declare constants

A promise represents a value that might not be ready yet but will be resolved in the future.

Which method is used to handle a successful promise result?

A .resolve()

B .catch()

C .finally()

D .then()

.then() is used to handle the successful completion of a promise.

What state is a promise in before it is fulfilled or rejected?

A Resolved

B Pending

C Rejected

D Completed

A promise starts in the pending state before it is either fulfilled or rejected.

How do promises help avoid callback hell?

A By chaining asynchronous operations cleanly

B By nesting callbacks deeper

C By ignoring errors

D By using synchronous code

Promises allow chaining with .then(), making asynchronous code easier to read and avoiding deeply nested callbacks.

Which method is used to catch errors in promises?

A .then()

B .finally()

C .catch()

D .error()

.catch() is used to handle errors in promise chains.

Explain why promises are used in JavaScript and how they improve asynchronous code.

Think about how promises make waiting for data easier and cleaner.

Describe the three states of a promise and what each means.

Consider what happens from start to finish of a promise.