Logo for jsDocs.io

mem

  • Version 10.0.0
  • Published
  • 17.9 kB
  • 2 dependencies
  • MIT license

Install

npm i mem
yarn add mem
pnpm add mem

Overview

Memoize functions - An optimization used to speed up consecutive function calls by caching the result of calls with identical input

Index

Functions

Interfaces

Functions

function mem

mem: <FunctionToMemoize extends AnyFunction, CacheKeyType>(
    fn: FunctionToMemoize,
    { cacheKey, cache, maxAge }?: Options<FunctionToMemoize, CacheKeyType>
) => FunctionToMemoize;

  • [Memoize](https://en.wikipedia.org/wiki/Memoization) functions - An optimization used to speed up consecutive function calls by caching the result of calls with identical input.

    Parameter fn

    Function to be memoized.

    Example 1

    import mem from 'mem';
    

    let index = 0;
    const counter = () => ++index;
    const memoized = mem(counter);
    

    memoized('foo');
    //=> 1
    

    // Cached as it's the same argument
    memoized('foo');
    //=> 1
    

    // Not cached anymore as the arguments changed
    memoized('bar');
    //=> 2
    

    memoized('bar');
    //=> 2

function memClear

memClear: (fn: AnyFunction) => void;

  • Clear all cached data of a memoized function.

    Parameter fn

    Memoized function.

function memDecorator

memDecorator: <FunctionToMemoize extends AnyFunction, CacheKeyType>(
    options?: Options<FunctionToMemoize, CacheKeyType>
) => (target: any, propertyKey: string, descriptor: PropertyDescriptor) => void;

  • Returns

    A [decorator](https://github.com/tc39/proposal-decorators) to memoize class methods or static class methods.

    Example 1

    import {memDecorator} from 'mem';
    

    class Example {
        index = 0
    

        @memDecorator()
        counter() {
            return ++this.index;
        }
    }
    

    class ExampleWithOptions {
        index = 0
    

        @memDecorator({maxAge: 1000})
        counter() {
            return ++this.index;
        }
    }

Interfaces

interface Options

interface Options<FunctionToMemoize extends AnyFunction, CacheKeyType> {}

    property cache

    readonly cache?: CacheStorage<CacheKeyType, ReturnType<FunctionToMemoize>>;

    • Use a different cache storage. Must implement the following methods: .has(key), .get(key), .set(key, value), .delete(key), and optionally .clear(). You could for example use a WeakMap instead or [quick-lru](https://github.com/sindresorhus/quick-lru) for a LRU cache.

      new Map()

      Example 1

      new WeakMap()

    property cacheKey

    readonly cacheKey?: (arguments_: Parameters<FunctionToMemoize>) => CacheKeyType;

    • Determines the cache key for storing the result based on the function arguments. By default, __only the first argument is considered__ and it only works with [primitives](https://developer.mozilla.org/en-US/docs/Glossary/Primitive).

      A cacheKey function can return any type supported by Map (or whatever structure you use in the cache option).

      You can have it cache **all** the arguments by value with JSON.stringify, if they are compatible:

      ``` import mem from 'mem';

      mem(function_, {cacheKey: JSON.stringify}); ```

      Or you can use a more full-featured serializer like [serialize-javascript](https://github.com/yahoo/serialize-javascript) to add support for RegExp, Date and so on.

      ``` import mem from 'mem'; import serializeJavascript from 'serialize-javascript';

      mem(function_, {cacheKey: serializeJavascript}); ```

      arguments_ => arguments_[0]

      Example 1

      arguments_ => JSON.stringify(arguments_)

    property maxAge

    readonly maxAge?: number;

    • Milliseconds until the cache expires.

      Infinity

    Package Files (1)

    Dependencies (2)

    Dev Dependencies (11)

    Peer Dependencies (0)

    No peer dependencies.

    Badge

    To add a badge like this onejsDocs.io badgeto your package's README, use the codes available below.

    You may also use Shields.io to create a custom badge linking to https://www.jsdocs.io/package/mem.

    • Markdown
      [![jsDocs.io](https://img.shields.io/badge/jsDocs.io-reference-blue)](https://www.jsdocs.io/package/mem)
    • HTML
      <a href="https://www.jsdocs.io/package/mem"><img src="https://img.shields.io/badge/jsDocs.io-reference-blue" alt="jsDocs.io"></a>