npm install @stdlib/utils-find

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.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.

var find = require( '@stdlib/utils-find' );

Finds elements in an array-like object that satisfy a test condition. The function accepts two options: k and returns.

• k: an integer which limits the number of elements returned and whose sign determines the direction in which to search. If set to a negative integer, the function searches from the last element to the first element.

• returns: specifies the type of result to return and may be one of three options: indices, values, *.

  • indices: indicates to return the element indices of those elements satisfying the search condition.
  • values: indicates to return the element values of those elements satisfying the search condition.
  • *: indicates to return both the element indices and values of those elements satisfying the search condition. The returned result is an array of arrays, where each sub-array is an index-value pair.

The callback is provided three arguments:

• element: the current element
• index: the current element's index
• array: the input array, typed array or string

By default, k is the length of arr and returns is set to indices.

var data = [ 30, 20, 50, 60, 10 ];

function greaterThan20( val ) {
    return val > 20;
}

var vals = find( data, greaterThan20 );
// returns [ 0, 2, 3 ]

data = 'Hello World';
function isUpperCase( val ) {
    return /[A-Z]/.test( val );
}

vals = find( data, isUpperCase );
// returns [ 0, 6 ]

To limit the number of results and specify that values should be returned,

var data = [ 30, 20, 50, 60, 10 ];

var opts = {
    'k': 2,
    'returns': 'values'
};

function condition( val ) {
    return val > 20;
}

var vals = find( data, opts, condition );
// returns [ 30, 50 ]

If no array elements satisfy the test condition, the function returns an empty array.

var data = [ 30, 20, 50, 60, 10 ];

var opts = {
    'k': 2,
    'returns': 'values'
};

function condition( val ) {
    return val > 1000;
}

var vals = find( data, opts, condition );
// returns []

To find the last two values satisfying a search condition,

var data = [ 30, 20, 50, 60, 10 ];

var opts = {
    'k': -2,
    'returns': 'values'
};

function condition( val ) {
    return val > 20;
}

var vals = find( data, opts, condition );
// returns [ 60, 50 ]

To explicitly specify that only indices are returned,

var data = [ 30, 20, 50, 60, 10 ];

var opts = {
    'k': -2,
    'returns': 'indices'
};

function condition( val ) {
    return val > 20;
}

var vals = find( data, opts, condition );
// returns [ 3, 2 ]

And to return both indices and values as index-value pairs,

var data = [ 30, 20, 50, 60, 10 ];

var opts = {
    'k': -2,
    'returns': '*'
};

function condition( val ) {
    return val > 20;
}

var vals = find( data, opts, condition );
// returns [ [3, 60], [2, 50] ]

This package is part of 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, see the main project repository.

See LICENSE.

Copyright © 2016-2024. The Stdlib Authors.