signal-exit vs Node.js process.on('exit') – which is better?

signal-exit is more reliable because it handles all exit causes, including signals, whereas process.on('exit') only fires on normal termination or explicit exit() calls. Use signal-exit for comprehensive cleanup in CLI tools or servers.

How to use signal-exit to close database connections on exit?

Register a handler with onExit that calls your database close method. For example: onExit(() => db.close()). Ensure to handle async cleanup if needed, but note handlers run synchronously before exit.

Does signal-exit work in browsers?

It provides a browser shim ('signal-exit/browser') that is a no-op, so it won't handle actual exits. It's meant for cross-environment code sharing, but browser exit handling requires window.onbeforeunload or similar APIs.

Can signal-exit prevent a Node.js process from exiting?

Only for signal exits by returning true in the handler, but not for numeric code exits or fatal errors. You must manually call process.kill() to preserve exit status if you capture a signal.

How do I remove a handler in signal-exit?

The onExit function returns a removal function; call it to unregister the handler. For instance: const remove = onExit(handler); later, remove() stops it from firing on exit.

What signals does signal-exit handle?

It handles fatal signals like SIGINT, SIGTERM, etc., that would cause the process to exit, but only if no other listeners are present. Check Node.js documentation for signal specifics.

signal-exit — Node.js Process Exit Handler

What is signal-exit?

signal-exit is a Node.js library that allows developers to register cleanup handlers that execute whenever a process exits, regardless of whether it's due to normal termination, an explicit exit call, or a fatal signal. It solves the problem of unreliable cleanup in Node.js applications by ensuring handlers run consistently across all exit paths.

Target Audience

Node.js developers building CLI tools, servers, or long-running processes that require reliable resource cleanup, logging, or finalization steps on exit.

Value Proposition

Developers choose signal-exit for its simplicity and reliability—it handles all exit scenarios with a minimal API, avoids common pitfalls in signal handling, and provides options like signal capture and ordered execution.

when you want to fire an event no matter how a process exits.

Use Cases

Best For

Ensuring cleanup code runs when a Node.js CLI tool exits
Handling graceful shutdown in long-running Node.js servers
Capturing and logging exit codes and signals for debugging
Managing resource cleanup (e.g., closing files, DB connections) on process termination
Building robust process managers or monitoring tools
Preventing resource leaks in Node.js applications with multiple exit paths

Not Ideal For

Browser applications requiring actual exit handling (the browser shim is a no-op)
Scenarios where preventing all process exits is critical (fatal exceptions or unhandled rejections cannot be stopped)
Projects that avoid monkeypatching due to library conflicts or security policies (with the alwaysLast option)
Simple, short-lived Node.js scripts with no cleanup needs (where built-in process events suffice)

Pros & Cons

Pros

Comprehensive Exit Coverage

Handles all exit causes including normal termination, explicit process.exit() calls, and fatal signals, ensuring cleanup runs reliably across scenarios as described in the README.

Simple Clean API

The onExit function with a removal return makes it easy to register and manage handlers without complex configuration, aligning with the library's philosophy of simplicity.

Signal Capture Control

Allows handlers to return true to capture and prevent signal exits, giving developers fine-grained control over exit behavior, as detailed in the Capturing Signal Exits section.

Robust Fallback Support

Includes a no-op implementation for unsuitable environments and a browser shim, providing cross-environment compatibility without breaking code, per the README's graceful fallbacks.

Cons

Limited Exit Prevention

Cannot prevent exits due to numeric codes, fatal exceptions, or unhandled promise rejections, as the README admits these are often already committed to exiting.

Intrusive Monkeypatching

The alwaysLast option monkeypatches process.emit, which can lead to conflicts with other libraries or debugging tools in complex Node.js environments.

Unloads After Handling

Once onExit handlers fire, the machinery unloads, so subsequent exits or signals in the same event loop might not be captured, limiting use in recursive exit scenarios.

What is signal-exit?

Target Audience

Node.js developers building CLI tools, servers, or long-running processes that require reliable resource cleanup, logging, or finalization steps on exit.

Value Proposition

Use Cases

Best For

Ensuring cleanup code runs when a Node.js CLI tool exits
Handling graceful shutdown in long-running Node.js servers
Capturing and logging exit codes and signals for debugging
Managing resource cleanup (e.g., closing files, DB connections) on process termination
Building robust process managers or monitoring tools
Preventing resource leaks in Node.js applications with multiple exit paths

Not Ideal For

Browser applications requiring actual exit handling (the browser shim is a no-op)
Scenarios where preventing all process exits is critical (fatal exceptions or unhandled rejections cannot be stopped)
Projects that avoid monkeypatching due to library conflicts or security policies (with the alwaysLast option)
Simple, short-lived Node.js scripts with no cleanup needs (where built-in process events suffice)

Pros & Cons

Pros

Comprehensive Exit Coverage

Handles all exit causes including normal termination, explicit process.exit() calls, and fatal signals, ensuring cleanup runs reliably across scenarios as described in the README.

Simple Clean API

The onExit function with a removal return makes it easy to register and manage handlers without complex configuration, aligning with the library's philosophy of simplicity.

Signal Capture Control

Allows handlers to return true to capture and prevent signal exits, giving developers fine-grained control over exit behavior, as detailed in the Capturing Signal Exits section.

Robust Fallback Support

Includes a no-op implementation for unsuitable environments and a browser shim, providing cross-environment compatibility without breaking code, per the README's graceful fallbacks.

Cons

Limited Exit Prevention

Cannot prevent exits due to numeric codes, fatal exceptions, or unhandled promise rejections, as the README admits these are often already committed to exiting.

Intrusive Monkeypatching

The alwaysLast option monkeypatches process.emit, which can lead to conflicts with other libraries or debugging tools in complex Node.js environments.

Unloads After Handling

Once onExit handlers fire, the machinery unloads, so subsequent exits or signals in the same event loop might not be captured, limiting use in recursive exit scenarios.

signal-exit

What is signal-exit?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?

signal-exit

What is signal-exit?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?