Global Objects in Node.js: Built-in Globals and Utilities

1. CommonJS Variables

These variables are only valid within the scope of CommonJS modules:

• __dirname: Path of the current module’s directory.
• __filename: Full path of the current file.
• exports: Module exports.
• module: Current module object.
• require(): Used to import modules.

2. AbortController and AbortSignal

Utility for canceling Promise-based operations. Key methods:

• abort(): Triggers the abort signal.
• AbortSignal.abort(): Creates an already-aborted signal.
• AbortSignal.timeout(): Aborts after a specified delay.
• AbortSignal.any(): Combines multiple signals.

3. Buffer and Blob

Buffer is used for handling binary data. Blob manages file-like data objects.

4. Browser-Compatible Utilities

• BroadcastChannel: Enables communication between contexts.
• MessageChannel, MessagePort, MessageEvent: Facilitate inter-thread or inter-process communication.
• EventTarget and CustomEvent: Event handling APIs.

5. Timer Functions

• clearTimeout()
• clearInterval()
• clearImmediate()

6. console

Used to print output to stdout and stderr.

7. fetch and Related Classes

Browser-compatible implementation of HTTP requests. Related classes:

• FormData
• Headers
• Request
• Response

8. global and globalThis

global is the legacy global object. globalThis is the modern, standardized replacement.

9. localStorage

Provides key-value storage similar to browsers. Limit: 10 MB.

10. Navigator

Partial implementation of the browser Navigator API. Key property: navigator.hardwareConcurrency shows the number of logical processors available.

Conclusion

Global objects in Node.js combine Node-specific features with browser-compatible APIs. Proper use of these globals enhances efficiency and simplifies application development.

1. Navigator Properties

• navigator.language: Preferred language of the Node.js instance.
• navigator.languages: Array of preferred languages.
• navigator.platform: Identifies the current platform.
• navigator.userAgent: Runtime name and version (e.g., "Node.js/21").
• navigator.locks: LockManager for coordinating shared resources.

2. Performance API

Classes like PerformanceEntry, PerformanceMark, PerformanceMeasure, and PerformanceObserver provide tools for measuring and monitoring performance. The performance object comes from the perf_hooks module.

3. process

The process object provides information and control over the Node.js runtime.

4. queueMicrotask()

Queues a microtask for execution. Similar to process.nextTick(), but managed by V8.

5. Stream APIs

• ReadableStream: Represents a readable stream.
• WritableStream: Represents a writable stream.
• Related classes include ReadableStreamDefaultReader and WritableStreamDefaultWriter.

6. Storage APIs

• sessionStorage: In-memory storage with a 10 MB limit.
• localStorage: Persistent storage backed by a file.
• Storage: Browser-compatible implementation.

7. structuredClone()

WHATWG standard method for deep cloning objects.

8. Encoding and Decoding

• TextEncoder and TextDecoder: Encode and decode text.
• Stream variants: TextEncoderStream and TextDecoderStream.

9. URL APIs

• URL: Standard class for managing addresses.
• URLSearchParams: Manage query parameters.
• URLPattern: Experimental support for URL pattern matching.

10. WebAssembly and WebSocket

WebAssembly enables low-level code execution, while WebSocket provides real-time communication compatible with browsers.

Conclusion

Global Objects in Node.js combine Node-specific features with browser-compatible APIs. These capabilities allow developers to use a unified set of tools across server-side and browser-like environments, enhancing flexibility and efficiency.