Question 1

Why does my Node app crash with an unhandled promise rejection?

Accepted Answer

A promise that rejects with nothing attached to handle it produces an unhandled rejection, and modern Node treats that as fatal by default. The process exits. This changed from earlier versions where it merely printed a warning, which is why older advice on the subject is misleading.

The reasoning behind the change is sound. An unhandled rejection means an error occurred and your code silently ignored it, so the program is continuing in a state it never accounted for. Crashing is safer than proceeding on bad assumptions.

The usual causes are all variations on losing track of a promise.

- Calling an async function without awaiting it. The call runs, and if it rejects there is nothing attached. This is the most common source, and it frequently appears in event handlers and callbacks where the surrounding function is not async.
- Awaiting inside a try block but starting the operation outside it, so the rejection happens before the try is entered.
- Creating several promises and awaiting them sequentially. If a later one rejects while an earlier await is still pending, the rejection is briefly unhandled. Collecting them and awaiting together avoids this.
- Forgetting a catch on a promise chain, particularly the last link.

The fix is to ensure every promise has a handler. Awaiting inside a try block is the clearest form. For anything deliberately started without awaiting, attach a catch explicitly, even if it only logs.

A process-level handler for unhandled rejections is worth adding for logging, since it tells you what crashed. It should not be used to swallow the error and keep running, which recreates exactly the unsafe behaviour the default is protecting against.

Question 2

What are effective strategies for handling errors in a Node.js application?

Accepted Answer

Effective Node.js error handling strategies include try-catch blocks, promise rejections, error middleware, event emitters, logging, and graceful shutdowns. These methods enhance application stability and user experience.

Question 3

What are the best practices for error handling in Node.js applications?

Accepted Answer

Implementing Node.js error handling best practices improves application reliability and user experience. Key methods include try-catch blocks, centralized error handling, and logging.

Question 4

What are the best practices for error handling in Node.js?

Accepted Answer

Implementing Node.js error handling best practices ensures robust applications that manage unexpected situations gracefully, improving user experience and stability.

Question 5

Why does my async function return a Promise instead of a value?

Accepted Answer

This is the defining behaviour of async functions rather than a mistake. Declaring a function async wraps its return value in a promise automatically. Returning a number from an async function

Question 6

What is the event loop in Node.js?

Accepted Answer

Node runs your JavaScript on a single thread. It achieves concurrency not by running code in parallel but by never waiting: operations that would block, such as reading a file or making a network

Question 7

Why is my Node.js application using so much memory?

Accepted Answer

High memory in a long-running process is either legitimate caching, a genuine leak, or garbage collection that has not needed to run yet. Distinguishing them is the first task, because the response

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