@stdlib/utils/shift/README.md

Standard utilities.

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# shift

> Remove and return the first element of a collection.

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## Usage

```javascript
var shift = require( '@stdlib/utils/shift' );
```

#### shift( collection )

Removes and returns the first element of a `collection`. A `collection` may be either an [`Array`][mdn-array], [`Typed Array`][mdn-typed-array], or an array-like [`Object`][mdn-object] (i.e., an [`Object`][mdn-object] having a valid writable `length` property). 

```javascript
var arr = [ 1.0, 2.0, 3.0, 4.0, 5.0 ];

var out = shift( arr );
// returns [ [ 2.0, 3.0, 4.0, 5.0 ], 1.0 ]

var bool = ( out[ 0 ] === arr );
// returns true

var lastValue = out[ 1 ];
// returns 1.0
```

In contrast to [`Array.prototype.shift`][mdn-array-shift] which returns only the removed element, the function also returns the shortened collection. For [typed arrays][mdn-typed-array] having a length greater than `0`, the returned collection is a new [typed array][mdn-typed-array] view.

```javascript
var Float64Array = require( '@stdlib/array/float64' );

var arr = new Float64Array( 2 );
arr[ 0 ] = 1.0;
arr[ 1 ] = 2.0;

var out = shift( arr );
// returns [ <Float64Array>[ 2.0 ], 1.0 ]

var bool = ( out[ 0 ] === arr );
// returns false

bool = ( out[ 0 ].buffer === arr.buffer );
// returns true

var lastValue = out[ 1 ];
// returns 1.0
```

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## Notes

-   When provided a [typed array][mdn-typed-array], the function does **not** change the underlying [`ArrayBuffer`][mdn-arraybuffer]. The function returns a new [typed array][mdn-typed-array] view whose length is one less than the input [typed array][mdn-typed-array] length. Accordingly, the function does **not** reduce the memory footprint of an input [typed array][mdn-typed-array].

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## Examples

<!-- eslint no-undef: "error" -->

```javascript
var Float64Array = require( '@stdlib/array/float64' );
var shift = require( '@stdlib/utils/shift' );

var arr;
var out;
var i;

arr = new Float64Array( 100 );
for ( i = 0; i < 100; i++ ) {
    out = shift( arr );
    arr = out[ 0 ];
    console.log( 'Length: %d', arr.length );
}
console.log( arr );
```

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* * *

## See Also

-   <span class="package-name">[`@stdlib/utils/pop`][@stdlib/utils/pop]</span><span class="delimiter">: </span><span class="description">remove and return the last element of a collection.</span>
-   <span class="package-name">[`@stdlib/utils/push`][@stdlib/utils/push]</span><span class="delimiter">: </span><span class="description">add one or more elements to the end of a collection.</span>
-   <span class="package-name">[`@stdlib/utils/unshift`][@stdlib/utils/unshift]</span><span class="delimiter">: </span><span class="description">add one or more elements to the beginning of a collection.</span>

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[mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array

[mdn-array-shift]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/shift

[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Typed_arrays

[mdn-arraybuffer]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer

[mdn-object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object

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[@stdlib/utils/pop]: https://github.com/stdlib-js/utils/tree/main/pop

[@stdlib/utils/push]: https://github.com/stdlib-js/utils/tree/main/push

[@stdlib/utils/unshift]: https://github.com/stdlib-js/utils/tree/main/unshift

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