Function composition.
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> [Function composition][function-composition].
``bash`
npm install @stdlib/utils-compose
`javascript`
var compose = require( '@stdlib/utils-compose' );
#### compose( ...fcn )
Returns a composite function. Starting from the right, the composite function evaluates each function and passes the result as an argument to the next function. The result of the leftmost function is the result of the whole.
`javascript
function a( x ) {
return 2 * x;
}
function b( x ) {
return x + 3;
}
function c( x ) {
return x / 5;
}
var f = compose( c, b, a );
var z = f( 6 ); // ((2*x)+3)/5
// returns 3
`
Only the rightmost function is explicitly permitted to accept multiple arguments. All other functions are evaluated as unary functions.
`javascript
function a( x, y ) {
return (x5) + (y3);
}
function b( r ) {
return r + 12;
}
var f = compose( b, a );
var z = f( 4, 6 );
// returns 50
`
- The function will throw if provided fewer than 2 input arguments.
`javascript
var compose = require( '@stdlib/utils-compose' );
function a( x, y ) {
return x * y;
}
function b( z ) {
return z + 5;
}
function c( r ) {
return r / 10;
}
var f = compose( c, b, a );
var v = f( 5, 3 );
// returns 2
`
*
- [@stdlib/utils-async/compose][@stdlib/utils/async/compose]: function composition.
*
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].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[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-compose/tree/deno
[deno-readme]: https://github.com/stdlib-js/utils-compose/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/utils-compose/tree/umd
[umd-readme]: https://github.com/stdlib-js/utils-compose/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/utils-compose/tree/esm
[esm-readme]: https://github.com/stdlib-js/utils-compose/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/utils-compose/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/utils-compose/main/LICENSE
[function-composition]: https://en.wikipedia.org/wiki/Function_composition_%28computer_science%29
[@stdlib/utils/async/compose]: https://www.npmjs.com/package/@stdlib/utils-async-compose