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https://github.com/stdlib-js/utils-async-every-by-right

Test whether all elements in a collection pass a test implemented by a predicate function, iterating from right to left.
https://github.com/stdlib-js/utils-async-every-by-right

all array-like async asynchronous collection every everyright iterate javascript node node-js nodejs predicate right stdlib test util utilities utility utils

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Test whether all elements in a collection pass a test implemented by a predicate function, iterating from right to left.

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README 

        



  

    About stdlib...

  

  
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# everyByRightAsync



[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] 



> Test whether all elements in a collection pass a test implemented by a predicate function, iterating from right to left.



## Installation



```bash

npm install @stdlib/utils-async-every-by-right

```



Alternatively,



-   To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).

-   If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).

-   For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).



The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.



To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.



## Usage



```javascript

var everyByRightAsync = require( '@stdlib/utils-async-every-by-right' );

```



#### everyByRightAsync( collection, \[options,] predicate, done )



Tests whether all elements in a `collection` pass a test implemented by a `predicate` function, iterating from right to left.



```javascript

function predicate( value, next ) {

    setTimeout( onTimeout, value );

    function onTimeout() {

        console.log( value );

        /* =>

            1000

            2500

            3000

        */



        next( null, true );

    }

}



function done( error, bool ) {

    if ( error ) {

        throw error;

    }

    console.log( bool );

    // => true

}



var arr = [ 1000, 2500, 3000 ];



everyByRightAsync( arr, predicate, done );

```



If a `predicate` function calls the `next` callback with a non-truthy test argument, the function stops processing any additional `collection` elements and returns `false` for the test result.



```javascript

function predicate( value, index, next ) {

    setTimeout( onTimeout, value );

    function onTimeout() {

        if ( index === 1 ) {

            return next( null, false );

        }

        next( null, true );

    }

}



function done( error, bool ) {

    if ( error ) {

        throw error;

    }

    console.log( bool );

    // => false

}



var arr = [ 1000, 2500, 3000 ];



everyByRightAsync( arr, predicate, done );

```



The function accepts the following `options`:



-   `limit`: the maximum number of pending invocations at any one time. Default: `infinity`.

-   `series`: `boolean` indicating whether to sequentially invoke the `predicate` function for each `collection` element. If `true`, the function sets `options.limit=1`. Default: `false`.

-   `thisArg`: the execution context for `predicate`.



By default, all elements are processed concurrently, which means that the function does **not** guarantee completion order. To process each `collection` element sequentially, set the `series` option to `true`.



```javascript

function predicate( value, next ) {

    setTimeout( onTimeout, value );

    function onTimeout() {

        console.log( value );

        /* =>

            3000

            2500

            1000

        */



        next( null, true );

    }

}



function done( error, bool ) {

    if ( error ) {

        throw error;

    }

    console.log( bool );

    // => true

}



var arr = [ 1000, 2500, 3000 ];



var opts = {

    'series': true

};



everyByRightAsync( arr, opts, predicate, done );

```



To limit the maximum number of pending function invocations, set the `limit` option.



```javascript

function predicate( value, next ) {

    setTimeout( onTimeout, value );

    function onTimeout() {

        console.log( value );

        /* =>

            2500

            3000

            1000

        */



        next( null, true );

    }

}



function done( error, bool ) {

    if ( error ) {

        throw error;

    }

    console.log( bool );

    // => true

}



var arr = [ 1000, 2500, 3000 ];



var opts = {

    'limit': 2

};



everyByRightAsync( arr, opts, predicate, done );

```



To set the execution context of the `predicate` function, set the `thisArg` option.



```javascript

function predicate( value, next ) {

    this.count += 1;

    setTimeout( onTimeout, value );

    function onTimeout() {

        next( null, true );

    }

}



var arr = [ 1000, 2500, 3000 ];



var context = {

    'count': 0

};



var opts = {

    'thisArg': context

};



everyByRightAsync( arr, opts, predicate, done );



function done( error, bool ) {

    if ( error ) {

        throw error;

    }

    console.log( bool );

    // => true



    console.log( context.count );

    // => 3

}

```



When invoked, the `predicate` function is provided a maximum of four arguments:



-   `value`: collection value.

-   `index`: collection index.

-   `collection`: the input `collection`.

-   `next`: a callback which should be called once the `predicate` function has finished processing a collection `value`.



The actual number of provided arguments depends on function `length`. If the `predicate` function accepts two arguments, the `predicate` function is provided `value` and `next`. If the `predicate` function accepts three arguments, the `predicate` function is provided `value`, `index`, and `next`. For every other `predicate` function signature, the `predicate` function is provided all four arguments.



```javascript

function predicate( value, i, collection, next ) {

    console.log( 'collection: %s. %d: %d', collection.join( ',' ), i, value );

    /* =>

        collection: 3000,2500,1000. 2: 3000

        collection: 3000,2500,1000. 1: 2500

        collection: 3000,2500,1000. 0: 1000

    */



    setTimeout( onTimeout, value );

    function onTimeout() {

        console.log( value );

        /* =>

            1000

            2500

            3000

        */



        next( null, true );

    }

}



function done( error, bool ) {

    if ( error ) {

        throw error;

    }

    console.log( bool );

    // => true

}



var arr = [ 1000, 2500, 3000 ];



everyByRightAsync( arr, predicate, done );

```



#### everyByRightAsync.factory( \[options,] predicate )



Returns a `function` which invokes a `predicate` function once for each element in a `collection`, iterating from right to left.



```javascript

function predicate( value, next ) {

    setTimeout( onTimeout, value );

    function onTimeout() {

        console.log( value );

        next( null, true );

    }

}



function done( error, bool ) {

    if ( error ) {

        throw error;

    }

    console.log( bool );

}



var f = everyByRightAsync.factory( predicate );



var arr1 = [ 1000, 2500, 3000 ];



f( arr1, done );

/* e.g., =>

    1000

    2500

    3000

    true

*/



var arr2 = [ 100, 250, 300 ];



f( arr2, done );

/* e.g., =>

    100

    250

    300

    true

*/

```



The function accepts the same `options` as `everyByRightAsync()`.



## Notes



-   A `collection` may be either an [`Array`][mdn-array], [`Typed Array`][mdn-typed-array], or an array-like [`Object`][mdn-object] (excluding `strings` and `functions`).

-   If a provided function calls the `next` callback with a truthy `error` argument, the function suspends execution and immediately calls the `done` callback for subsequent `error` handling.

-   The function does **not** support dynamic `collection` resizing.

-   The function does **not** skip `undefined` elements.

-   If provided an empty `collection`, the function calls the `done` callback with `true` as the test result.

-   **Neither** `everyByRightAsync` nor the function returned by the `factory` method **guarantee** asynchronous execution. To guarantee asynchrony, wrap the `done` callback in a function which either executes at the end of the current stack (e.g., `nextTick`) or during a subsequent turn of the event loop (e.g., `setImmediate`, `setTimeout`).



## Examples



```javascript

var resolve = require( 'path' ).resolve;

var readFile = require( '@stdlib/fs-read-file' );

var everyByRightAsync = require( '@stdlib/utils-async-every-by-right' );



var files = [

    resolve( __dirname, 'package.json' ),

    resolve( __dirname, 'README.md' )

];



function done( error, bool ) {

    if ( error ) {

        throw error;

    }

    if ( bool ) {

        console.log( 'Successfully read all files.' );

    } else {

        console.log( 'Was unable to read all files.' );

    }

}



function predicate( file, next ) {

    var opts = {

        'encoding': 'utf8'

    };

    readFile( file, opts, onFile );



    function onFile( error ) {

        if ( error ) {

            return next( null, false );

        }

        next( null, true );

    }

}



everyByRightAsync( files, predicate, done );

```



* * *



## See Also



-   [`@stdlib/utils-async/any-by-right`][@stdlib/utils/async/any-by-right]: test whether at least one element in a collection passes a test implemented by a predicate function, iterating from right to left.

-   [`@stdlib/utils-async/every-by`][@stdlib/utils/async/every-by]: test whether all elements in a collection pass a test implemented by a predicate function.

-   [`@stdlib/utils-every-by-right`][@stdlib/utils/every-by-right]: test whether all elements in a collection pass a test implemented by a predicate function, iterating from right to left.

-   [`@stdlib/utils-async/for-each-right`][@stdlib/utils/async/for-each-right]: invoke a function once for each element in a collection, iterating from right to left.

-   [`@stdlib/utils-async/none-by-right`][@stdlib/utils/async/none-by-right]: test whether all elements in a collection fail a test implemented by a predicate function, iterating from right to left.

-   [`@stdlib/utils-async/some-by-right`][@stdlib/utils/async/some-by-right]: test whether a collection contains at least `n` elements which pass a test implemented by a predicate function, iterating from right to left.



* * *



## Notice



This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.



For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].



#### Community



[![Chat][chat-image]][chat-url]



---



## License



See [LICENSE][stdlib-license].



## Copyright



Copyright © 2016-2024. The Stdlib [Authors][stdlib-authors].



[npm-image]: http://img.shields.io/npm/v/@stdlib/utils-async-every-by-right.svg

[npm-url]: https://npmjs.org/package/@stdlib/utils-async-every-by-right



[test-image]: https://github.com/stdlib-js/utils-async-every-by-right/actions/workflows/test.yml/badge.svg?branch=main

[test-url]: https://github.com/stdlib-js/utils-async-every-by-right/actions/workflows/test.yml?query=branch:main



[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/utils-async-every-by-right/main.svg

[coverage-url]: https://codecov.io/github/stdlib-js/utils-async-every-by-right?branch=main



[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg

[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im



[stdlib]: https://github.com/stdlib-js/stdlib



[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors



[umd]: https://github.com/umdjs/umd

[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules



[deno-url]: https://github.com/stdlib-js/utils-async-every-by-right/tree/deno

[deno-readme]: https://github.com/stdlib-js/utils-async-every-by-right/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/utils-async-every-by-right/tree/umd

[umd-readme]: https://github.com/stdlib-js/utils-async-every-by-right/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/utils-async-every-by-right/tree/esm

[esm-readme]: https://github.com/stdlib-js/utils-async-every-by-right/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/utils-async-every-by-right/blob/main/branches.md



[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/utils-async-every-by-right/main/LICENSE



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



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



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



[@stdlib/utils/async/any-by-right]: https://github.com/stdlib-js/utils-async-any-by-right



[@stdlib/utils/async/every-by]: https://github.com/stdlib-js/utils-async-every-by



[@stdlib/utils/every-by-right]: https://github.com/stdlib-js/utils-every-by-right



[@stdlib/utils/async/for-each-right]: https://github.com/stdlib-js/utils-async-for-each-right



[@stdlib/utils/async/none-by-right]: https://github.com/stdlib-js/utils-async-none-by-right



[@stdlib/utils/async/some-by-right]: https://github.com/stdlib-js/utils-async-some-by-right