# isgzipBuffer
> Test if a value is a [gzip][gzip-rfc-1952] buffer.
## Usage
```javascript
var isgzipBuffer = require( '@stdlib/assert/is-gzip-buffer' );
```
#### isgzipBuffer( value )
Tests if a value is a [`gzip`][gzip-rfc-1952] buffer.
```javascript
var Uint8Array = require( '@stdlib/array/uint8' );
var buf = new Uint8Array( 20 );
buf[ 0 ] = 31; // 0x1f => magic number
buf[ 1 ] = 139; // 0x8b
buf[ 2 ] = 8; // 0x08 => compression method
var bool = isgzipBuffer( buf );
// returns true
bool = isgzipBuffer( [] );
// returns false
```
## Notes
- A [gzip][gzip-rfc-1952] buffer is defined as either a Node.js [`Buffer`][@stdlib/buffer/ctor] or [`Uint8Array`][@stdlib/array/uint8] which contains a 10-byte header, a body containing the compressed payload, and an 8-byte footer containing a CRC-32 checksum and the length of the original uncompressed data, modulo `2^32`.
- This function only examines the 10-byte header to ensure the header includes the expected magic number and compression method. The function does not perform an integrity check.
## Examples
```javascript
var Float32Array = require( '@stdlib/array/float32' );
var Float64Array = require( '@stdlib/array/float64' );
var Int8Array = require( '@stdlib/array/int8' );
var Int16Array = require( '@stdlib/array/int16' );
var Int32Array = require( '@stdlib/array/int32' );
var Uint8Array = require( '@stdlib/array/uint8' );
var Uint8ClampedArray = require( '@stdlib/array/uint8c' );
var Uint16Array = require( '@stdlib/array/uint16' );
var Uint32Array = require( '@stdlib/array/uint32' );
var isgzipBuffer = require( '@stdlib/assert/is-gzip-buffer' );
var buf = new Uint8Array( 20 );
buf[ 0 ] = 31; // 0x1f => magic number
buf[ 1 ] = 139; // 0x8b
buf[ 2 ] = 8; // 0x08 => compression method
var bool = isgzipBuffer( buf );
// returns true
bool = isgzipBuffer( new Float32Array( 20 ) );
// returns false
bool = isgzipBuffer( new Int8Array( 20 ) );
// returns false
bool = isgzipBuffer( new Uint8Array( 20 ) );
// returns false
bool = isgzipBuffer( new Uint8ClampedArray( 20 ) );
// returns false
bool = isgzipBuffer( new Int16Array( 20 ) );
// returns false
bool = isgzipBuffer( new Uint16Array( 20 ) );
// returns false
bool = isgzipBuffer( new Int32Array( 20 ) );
// returns false
bool = isgzipBuffer( new Uint32Array( 20 ) );
// returns false
bool = isgzipBuffer( new Float64Array( 20 ) );
// returns false
bool = isgzipBuffer( new Array( 20 ) );
// returns false
bool = isgzipBuffer( {} );
// returns false
bool = isgzipBuffer( null );
// returns false
```
[gzip-rfc-1952]: https://tools.ietf.org/html/rfc1952
[@stdlib/buffer/ctor]: https://www.npmjs.com/package/@stdlib/buffer-ctor
[@stdlib/array/uint8]: https://www.npmjs.com/package/@stdlib/array-uint8