# Bytes per Element
> Return the number of bytes per element provided an underlying [array data type][@stdlib/ndarray/dtypes].
## Usage
```javascript
var bytesPerElement = require( '@stdlib/ndarray/base/bytes-per-element' );
```
#### bytesPerElement( dtype )
Returns the number of bytes per element provided an underlying [array data type][@stdlib/ndarray/dtypes].
```javascript
var nbytes = bytesPerElement( 'float64' );
// returns 8
nbytes = bytesPerElement( 'generic' );
// returns null
```
If provided an unknown or unsupported data type, the function returns `null`.
```javascript
var nbytes = bytesPerElement( 'foobar' );
// returns null
```
## Examples
```javascript
var bytesPerElement = require( '@stdlib/ndarray/base/bytes-per-element' );
var dtypes;
var nbytes;
var i;
dtypes = [
'float64',
'float32',
'int8',
'uint8',
'uint8c',
'int16',
'uint16',
'int32',
'uint32',
'binary',
'generic',
'foobar'
];
for ( i = 0; i < dtypes.length; i++ ) {
nbytes = bytesPerElement( dtypes[ i ] );
nbytes = ( nbytes ) ? nbytes+' bytes' : 'null';
console.log( '%s => %s', dtypes[ i ], nbytes );
}
```
[@stdlib/ndarray/dtypes]: https://www.npmjs.com/package/@stdlib/ndarray/tree/main/dtypes