nodejs/doc/api/globals.md

Global Objects

These objects are available in all modules. The following variables may appear to be global but are not. They exist only in the scope of modules, see the module system documentation:

• __dirname
• __filename
• exports
• module
• require()

The objects listed here are specific to Node.js. There are a number of built-in objects that are part of the JavaScript language itself, which are also globally accessible.

Class: Buffer

• {Function}

Used to handle binary data. See the buffer section.

__dirname

This variable may appear to be global but is not. See __dirname.

__filename

This variable may appear to be global but is not. See __filename.

clearImmediate(immediateObject)

clearImmediate is described in the timers section.

clearInterval(intervalObject)

clearInterval is described in the timers section.

clearTimeout(timeoutObject)

clearTimeout is described in the timers section.

console

• {Object}

Used to print to stdout and stderr. See the console section.

exports

This variable may appear to be global but is not. See exports.

global

• {Object} The global namespace object.

In browsers, the top-level scope is the global scope. This means that within the browser var something will define a new global variable. In Node.js this is different. The top-level scope is not the global scope; var something inside a Node.js module will be local to that module.

module

This variable may appear to be global but is not. See module.

process

• {Object}

The process object. See the process object section.

queueMicrotask(callback)

• callback {Function} Function to be queued.

The queueMicrotask() method queues a microtask to invoke callback. If callback throws an exception, the process object 'uncaughtException' event will be emitted.

The microtask queue is managed by V8 and may be used in a similar manner to the process.nextTick() queue, which is managed by Node.js. The process.nextTick() queue is always processed before the microtask queue within each turn of the Node.js event loop.

// Here, `queueMicrotask()` is used to ensure the 'load' event is always
// emitted asynchronously, and therefore consistently. Using
// `process.nextTick()` here would result in the 'load' event always emitting
// before any other promise jobs.

DataHandler.prototype.load = async function load(key) {
  const hit = this._cache.get(url);
  if (hit !== undefined) {
    queueMicrotask(() => {
      this.emit('load', hit);
    });
    return;
  }

  const data = await fetchData(key);
  this._cache.set(url, data);
  this.emit('load', data);
};

require()

This variable may appear to be global but is not. See require().

setImmediate(callback[, ...args])

setImmediate is described in the timers section.

setInterval(callback, delay[, ...args])

setInterval is described in the timers section.

setTimeout(callback, delay[, ...args])

setTimeout is described in the timers section.

TextDecoder

The WHATWG TextDecoder class. See the TextDecoder section.

TextEncoder

The WHATWG TextEncoder class. See the TextEncoder section.

URL

The WHATWG URL class. See the URL section.

URLSearchParams

The WHATWG URLSearchParams class. See the URLSearchParams section.

WebAssembly

• {Object}

The object that acts as the namespace for all W3C WebAssembly related functionality. See the Mozilla Developer Network for usage and compatibility.