memoize-id

memoize-id [![npm][npm-badge]][npm] [![Build Status][travis-badge]][travis]

Memoize a function by the identity of its arguments, using [ES2015 Map][Map].

Installation

npm install memoize-id

Note: ES2015 [Symbol][] and [Map][] must be available where memoize-id is used. Refer to ECMAScript 6 compatibility table.

Usage

import memoize from 'memoize-id';
// or:
// const memoize = require('memoize-id').default;

let i = 0;
function fn(foo, bar, baz) {
  i += 1;
  return {
    args: [foo, bar, baz],
    i,
  };
}
const memoizedFn = memoize(fn);

console.log(i);
// 0
const v1 = memoizedFn('foo', 'bar', 'baz');
console.log(v1);
// { args: ['foo', 'bar', 'baz'], i: 1 }
console.log(i);
// 1
const v2 = memoizedFn('foo', 'bar', 'baz');
console.log(v2);
// { args: ['foo', 'bar', 'baz'], i: 1 }
console.log(v1 === v2);
// true
console.log(i);
// 1
const v3 = memoizedFn('foo', 'qux', 'baz');
console.log(v3);
// { args: ['foo', 'qux', 'baz'], i: 2 }
console.log(i);
// 2
console.log(v1 == v3);
// false

[Map]: (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map [Symbol]: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Symbol [npm]: https://www.npmjs.com/package/memoize-id [npm-badge]: https://img.shields.io/npm/v/memoize-id.svg [travis]: https://travis-ci.org/elliottsj/memoize-id [travis-badge]: https://travis-ci.org/elliottsj/memoize-id.svg?branch=master