About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

memoize

Memoize a function.

Installation

npm install @stdlib/utils-memoize

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.

Usage

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

memoize( fcn[, hashFunction] )

Memoizes a function.

var randu = require( '@stdlib/random-base-randu' );

function rand( n ) {
    return n * randu();
}

var memoized = memoize( rand );

var v1 = memoized( 5 );
var v2 = memoized( 5 );

var bool = ( v1 === v2 );
// returns true

By default, the implementation serializes provided arguments as a string and stores results using the string as an identifier. To use a custom hash function, provide a hash function argument.

function add( obj ) {
    return obj.x + obj.y + obj.z;
}

obj = {
    'x': 3,
    'y': 4,
    'z': 5
};

// Default behavior...

var memoized = memoize( add );

var v1 = memoized( obj );
// returns 12

var str = obj.toString();
// returns '[object Object]'

var v2 = memoized.cache[ str ];
// returns 12

obj.x = 1000;

var v3 = memoized( obj );
// returns 12

// Custom hash function...

function hashFunction( args ) {
    return JSON.stringify( args );
}

memoized = memoize( add, hashFunction );

v1 = memoized( obj );
// returns 1009

str = hashFunction( [ obj ] );
// returns '[{"x":1000,"y":4,"z":5}]'

v2 = memoized.cache[ str ];
// returns 1009

obj.x = 6;

v3 = memoized( obj );
// returns 15

memoized.cache

Results cache. Note that, while the property is read-only, cache contents may be modified independently of the memoized function.

function beep( x ) {
    throw new Error( 'boop' );
}

var memoized = memoize( beep );

var cache = memoized.cache;
// returns {}

// Modify the cache:
cache[ 'bop' ] = 'bip';

var str = memoized( 'bop' );
// returns 'bip'

Notes

• The implementation does not set the length of the returned function. Accordingly, the returned function length is always 0.
• The evaluation context is always null.

Examples

var randu = require( '@stdlib/random-base-randu' );
var floor = require( '@stdlib/math-base-special-floor' );
var memoize = require( '@stdlib/utils-memoize' );

var fcn;
var n;
var v;
var i;

function rand( n ) {
    return n * randu();
}

fcn = memoize( rand );

for ( i = 0; i < 100; i++ ) {
    n = floor( randu() * 5 );
    v = fcn( n );
    console.log( 'rand(%d) = %d', n, v );
}

---

Notice

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.

Community

---

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.