153 lines
5.0 KiB
Markdown
153 lines
5.0 KiB
Markdown
<!--
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@license Apache-2.0
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Copyright (c) 2018 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# push
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> Add one or more elements to the end of a collection.
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<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
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<section class="intro">
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</section>
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<!-- /.intro -->
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<!-- Package usage documentation. -->
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<section class="usage">
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## Usage
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```javascript
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var push = require( '@stdlib/utils/push' );
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```
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#### push( collection, ...items )
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Adds one or more elements to the end 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).
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```javascript
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var arr = [ 1.0, 2.0, 3.0, 4.0, 5.0 ];
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var out = push( arr, 6.0, 7.0 );
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// returns [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0 ]
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var bool = ( out === arr );
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// returns true
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```
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In contrast to [`Array.prototype.push`][mdn-array-push], the function returns the extended collection, rather than the collection length. For [typed arrays][mdn-typed-array], the returned value is a new [typed array][mdn-typed-array] view whose underlying [`ArrayBuffer`][mdn-arraybuffer] may **not** equal the underlying [`ArrayBuffer`][mdn-arraybuffer] for the input `collection`.
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```javascript
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var ArrayBuffer = require( '@stdlib/array/buffer' );
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var Float64Array= require( '@stdlib/array/float64' );
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var buf = new ArrayBuffer( 3*8 ); // 8 bytes per double
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var arr = new Float64Array( buf, 0, 2 );
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arr[ 0 ] = 1.0;
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arr[ 1 ] = 2.0;
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var out = push( arr, 3.0 );
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// returns <Float64Array>[ 1.0, 2.0, 3.0 ]
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var bool = ( out === arr );
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// returns false
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bool = ( out.buffer === arr.buffer );
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// returns true
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out = push( out, 4.0 );
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// returns <Float64Array>[ 1.0, 2.0, 3.0, 4.0 ]
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bool = ( out.buffer === arr.buffer );
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// returns false
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```
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</section>
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<!-- /.usage -->
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<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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## Notes
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- The function adds one or more elements to a [typed array][mdn-typed-array] by setting values in the underlying [`ArrayBuffer`][mdn-arraybuffer]. If an [`ArrayBuffer`][mdn-arraybuffer] does not have enough bytes in which to store all elements, the function allocates a new [`ArrayBuffer`][mdn-arraybuffer] capable of holding `2^n` elements, where `n` is the next power of `2`. This procedure is similar to how environments internally handle dynamic memory allocation for [`Arrays`][mdn-array].
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- Beware when providing [typed arrays][mdn-typed-array] which are views pointing to a shared (or pooled) [`ArrayBuffer`][mdn-arraybuffer]. Because the function sets [`ArrayBuffer`][mdn-arraybuffer] bytes outside of a provided [view][mdn-typed-array], the function may overwrite bytes belonging to one or more external views. This could be a potential **security vulnerability**. Prefer providing [typed arrays][mdn-typed-array] which have an exclusive [`ArrayBuffer`][mdn-arraybuffer]; otherwise, be sure to plan for and guard against mutated state.
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</section>
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<!-- /.notes -->
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<!-- Package usage examples. -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var Float64Array= require( '@stdlib/array/float64' );
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var push = require( '@stdlib/utils/push' );
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var arr;
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var i;
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arr = new Float64Array();
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for ( i = 0; i < 100; i++ ) {
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arr = push( arr, i );
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}
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console.log( arr );
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```
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</section>
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<!-- /.examples -->
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<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="references">
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</section>
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<!-- /.references -->
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<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="links">
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[mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
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[mdn-array-push]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push
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[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Typed_arrays
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[mdn-arraybuffer]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer
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[mdn-object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
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</section>
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<!-- /.links -->
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