# Global Objects

<!-- type=misc -->

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.

## global

<!-- type=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 io.js this is different. The top-level scope is not the global
scope; `var something` inside an io.js module will be local to that module.

## process

<!-- type=global -->

* {Object}

The process object. See the [process object][] section.

## console

<!-- type=global -->

* {Object}

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

## Class: Buffer

<!-- type=global -->

* {Function}

Used to handle binary data. See the [buffer section][]

## require()

<!-- type=var -->

* {Function}

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

### 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.

### 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.

### 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 io.js by compiling them on-demand.
However, in practice, there are much better ways to do this, such as
loading modules via some other io.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.

## __filename

<!-- type=var -->

* {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 `iojs example.js` from `/Users/mjr`

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

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

## __dirname

<!-- type=var -->

* {String}

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

Example: running `iojs example.js` from `/Users/mjr`

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

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


## module

<!-- type=var -->

* {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.

## exports

<!-- type=var -->

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.

See the [module section][] for more information.

## setTimeout(cb, ms)

Run callback `cb` after *at least* `ms` milliseconds. The actual delay depends
on external factors like OS timer granularity and system load.

The timeout must be in the range of 1-2,147,483,647 inclusive. If the value is
outside that range, it's changed to 1 millisecond. Broadly speaking, a timer
cannot span more than 24.8 days.

Returns an opaque value that represents the timer.

## clearTimeout(t)

Stop a timer that was previously created with `setTimeout()`. The callback will
not execute.

## setInterval(cb, ms)

Run callback `cb` repeatedly every `ms` milliseconds. Note that the actual
interval may vary, depending on external factors like OS timer granularity and
system load. It's never less than `ms` but it may be longer.

The interval must be in the range of 1-2,147,483,647 inclusive. If the value is
outside that range, it's changed to 1 millisecond. Broadly speaking, a timer
cannot span more than 24.8 days.

Returns an opaque value that represents the timer.

## clearInterval(t)

Stop a timer that was previously created with `setInterval()`. The callback
will not execute.

<!--type=global-->

The timer functions are global variables. See the [timers][] section.

[buffer section]: buffer.html
[module section]: modules.html
[module system documentation]: modules.html
[Modules]: modules.html#modules_modules
[process object]: process.html#process_process
[console]: console.html
[timers]: timers.html