npm install @stdlib/utils-some-by

Alternatively,

• To load the package in a website via ascript tag without installation and bundlers, use theES Module available on theesm branch (seeREADME).
• If you are using Deno, visit thedeno branch (seeREADME for usage intructions).
• For use in Observable, or in browser/node environments, use theUniversal Module Definition (UMD) build available on theumd branch (seeREADME).

Thebranches.md 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.

varsomeBy=require('@stdlib/utils-some-by');

Tests whether acollection contains at leastn elements which pass a test implemented by apredicate function.

functionisNegative(value){return(value<0);}vararr=[1,-2,3,4,-1];varbool=someBy(arr,2,isNegative);// returns true

Once the function findsn successful elements, the functionimmediately returnstrue.

functionisPositive(value){if(value<0){thrownewError('should never reach this line');}return(value>0);}vararr=[1,2,-3,4];varbool=someBy(arr,2,isPositive);// returns true

The invokedfunction is provided three arguments:

• value: collection element.
• index: collection index.
• collection: input collection.

To set the function execution context, provide athisArg.

functionsum(value){this.sum+=value;this.count+=1;return(value<0);}vararr=[1,2,3,4,-5];varcontext={'sum':0,'count':0};varbool=someBy(arr,1,sum,context);// returns truevarmean=context.sum/context.count;// returns 1.0

• Acollection may be either anArray,Typed Array, or an array-likeObject (excludingstrings andfunctions).

• If provided an emptycollection, the function returnsfalse.

  functionalwaysTrue(){returntrue;}varbool=someBy([],1,alwaysTrue);// returns false

• The function doesnot skipundefined elements.

  functionlog(value,index){console.log('%s: %s',index,value);return(value<0);}vararr=[1,,,4,-1];varbool=someBy(arr,1,log);/* =>    0: 1    1: undefined    2: undefined    3: 4    4: -1*/

• The function provides limited support for dynamic collections (i.e., collections whoselength changes during execution).

• @stdlib/utils-any-by:test whether at least one element in a collection passes a test implemented by a predicate function.
• @stdlib/utils-every-by:test whether all elements in a collection pass a test implemented by a predicate function.
• @stdlib/utils-for-each:invoke a function for each element in a collection.
• @stdlib/utils-none-by:test whether all elements in a collection fail a test implemented by a predicate function.
• @stdlib/utils-async/some-by:test whether a collection containsn elements which pass a test implemented by a predicate function.
• @stdlib/utils-some-by-right:test whether a collection contains at leastn elements which pass a test implemented by a predicate function, iterating from right to left.

This package is part ofstdlib, 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 developstdlib, see the main projectrepository.

SeeLICENSE.

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