# offset
> Return the index offset specifying the underlying buffer index of the first iterated [ndarray][@stdlib/ndarray/ctor] element.
## Usage
```javascript
var offset = require( '@stdlib/ndarray/offset' );
```
#### offset( x )
Returns the index offset specifying the underlying buffer index of the first iterated [ndarray][@stdlib/ndarray/ctor] element.
```javascript
var zeros = require( '@stdlib/ndarray/zeros' );
var x = zeros( [ 3, 2, 3 ] );
// returns
var n = offset( x );
// returns 0
```
## Examples
```javascript
var zeros = require( '@stdlib/ndarray/zeros' );
var slice = require( '@stdlib/ndarray/slice' );
var E = require( '@stdlib/slice/multi' );
var S = require( '@stdlib/slice/ctor' );
var offset = require( '@stdlib/ndarray/offset' );
// Create an array:
var x = zeros( [ 10, 10, 10, 10 ] );
// returns
// Define some slices:
var slices = [
// :,:,:,:
E( null, null, null, null ),
// 5:10,4,2:4,::-1
E( S( 5, 10 ), 4, S( 2, 4 ), S( null, null, -1 ) ),
// :,:,2,:
E( null, null, 2, null ),
// 1,2,3,:
E( 1, 2, 3, null ),
// 1,3,::2,4::2
E( 1, 3, S( null, null, 2 ), S( 4, null, 2 ) )
];
// Determine the index offset for each slice...
var s;
var i;
for ( i = 0; i < slices.length; i++ ) {
s = slice( x, slices[ i ] );
console.log( '%s => %d', s.shape.join( 'x' ), offset( s ) );
}
```
[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray/tree/main/ctor
[@stdlib/ndarray/array]: https://github.com/stdlib-js/ndarray/tree/main/array
[@stdlib/ndarray/shape]: https://github.com/stdlib-js/ndarray/tree/main/shape
[@stdlib/ndarray/strides]: https://github.com/stdlib-js/ndarray/tree/main/strides