Async/await syntax in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the async keyword do when placed before a function?

It makes the function return a Promise automatically and allows the use of await inside it to pause execution until a Promise resolves.

beginner

How does the await keyword work inside an async function?

It pauses the function execution until the awaited Promise settles, then returns the resolved value or throws an error if rejected.

intermediate

Why should you use try/catch blocks with async/await?

Because await can throw errors if the Promise rejects, so try/catch helps handle those errors gracefully.

intermediate

What happens if you use await outside of an async function?

It causes a syntax error because await can only be used inside functions declared with async or in top-level modules supporting top-level await.

advanced

How can you run multiple asynchronous operations in parallel using async/await?

Start all Promises without awaiting them immediately, then use await Promise.all([...]) to wait for all to finish together.

What does the async keyword do to a function?

A Makes the function return a Promise

B Makes the function synchronous

C Prevents errors inside the function

D Automatically logs function output

The async keyword makes the function return a Promise, enabling the use of await inside.

Where can you use the await keyword?

A Anywhere in the code

B Only inside <code>async</code> functions or top-level modules

C Only inside <code>try/catch</code> blocks

D Only in synchronous functions

await can only be used inside async functions or in modules that support top-level await.

What is the best way to handle errors when using await?

A Use <code>setTimeout</code>

B Ignore errors

C Use <code>console.log</code> only

D Use <code>try/catch</code> blocks

Using try/catch blocks lets you catch and handle errors from rejected Promises when using await.

How do you run multiple async tasks in parallel with async/await?

A Start all Promises, then await <code>Promise.all</code>

B Await each Promise one after another

C Use <code>setInterval</code>

D Use nested <code>async</code> functions

Starting all Promises first and then awaiting Promise.all runs them in parallel efficiently.

What happens if an awaited Promise rejects and you don't catch the error?

A The function will ignore the error silently

B The Promise will resolve anyway

C The error will be unhandled and may crash the program

D The program will pause indefinitely

If you don't catch errors from rejected Promises, they remain unhandled and can crash your program.

Explain how async and await work together to handle asynchronous code in Node.js.

Think about how you wait for a friend to arrive before starting an activity.

Describe how to handle errors when using await in your code.

Imagine catching a ball so it doesn't fall and break.