node/doc/api/globals.md

Global Objects

These objects are available in all modules. Some of these objects aren't actually in the global scope but in the module scope - this will be noted.

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

• {String}

The name of the directory that the currently executing script resides in.

Example: running node example.js from /Users/mjr

console.log(__dirname);
// Prints: /Users/mjr

__dirname isn't actually a global but rather local to each module.

For instance, given two modules: a and b, where b is a dependency of a and there is a directory structure of:

• /Users/mjr/app/a.js
• /Users/mjr/app/node_modules/b/b.js

References to __dirname within b.js will return /Users/mjr/app/node_modules/b while references to __dirname within a.js will return /Users/mjr/app.

__filename

• {String}

The filename of the code being executed. This is the resolved absolute path of this code file. For a main program this is not necessarily the same filename used in the command line. The value inside a module is the path to that module file.

Example: running node example.js from /Users/mjr

console.log(__filename);
// Prints: /Users/mjr/example.js

__filename isn't actually a global but rather local to each module.

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

A reference to the module.exports that is shorter to type. See module system documentation for details on when to use exports and when to use module.exports.

exports isn't actually a global but rather local to each module.

See the module system documentation for more information.

global

• {Object} The global namespace object.

In browsers, the top-level scope is the global scope. That means that in browsers if you're in the global scope var something will define a global variable. In Node.js this is different. The top-level scope is not the global scope; var something inside an Node.js module will be local to that module.

module

• {Object}

A reference to the current module. In particular module.exports is used for defining what a module exports and makes available through require().

module isn't actually a global but rather local to each module.

See the module system documentation for more information.

process

• {Object}

The process object. See the process object section.

require()

• {Function}

To require modules. See the Modules section. require isn't actually a global but rather local to each module.

require.cache

• {Object}

Modules are cached in this object when they are required. By deleting a key value from this object, the next require will reload the module. Note that this does not apply to native addons, for which reloading will result in an Error.

require.extensions

Stability: 0 - Deprecated

• {Object}

Instruct require on how to handle certain file extensions.

Process files with the extension .sjs as .js:

require.extensions['.sjs'] = require.extensions['.js'];

Deprecated In the past, this list has been used to load non-JavaScript modules into Node.js by compiling them on-demand. However, in practice, there are much better ways to do this, such as loading modules via some other Node.js program, or compiling them to JavaScript ahead of time.

Since the module system is locked, this feature will probably never go away. However, it may have subtle bugs and complexities that are best left untouched.

Note that the number of file system operations that the module system has to perform in order to resolve a require(...) statement to a filename scales linearly with the number of registered extensions.

In other words, adding extensions slows down the module loader and should be discouraged.

require.resolve()

Use the internal require() machinery to look up the location of a module, but rather than loading the module, just return the resolved filename.

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.