Function memoize

Returns memoized version of the parameter function fn. The memoized function will return cached value as long as the arguments of the call have the same tracked values as the last time.

Memoized function has two cache levels:

• A WeakMap by first object parameter
• Global cache that only holds the last execution result.

See

IMemoizeOptions for details on available options.

Returns

memoized function.

Example

With two parameters:

import { memoize } from '@indutny/sneequals';

const fn = memoize((a, b) => ({ result: a.value + b.value }));

// Prints `{ result: 3 }`
const answer = fn({ value: 1 }, { value: 2 });
console.log(answer);

const cachedAnswer = fn({ value: 1 }, { value: 2 });

// Even though the input objects are different the `cachedResult` is the
// same since the tracked properties didn't change.
// Prints `true`.
console.log(answer === cachedAnswer);

Example

With react-redux and an id lookup. (Taken from proxy-memoize.)

import { useCallback } from 'react';
import { useSelector } from 'react-redux';
import { memoize } from '@indutny/sneequals';

const Component = ({ id }) => {
  const { score, title } = useSelector(useCallback(memoize(state => ({
    score: getScore(state),
    title: state.titles[id],
  })), [id]));
  return <div>{score.score} {score.createdAt} {title}</div>;
};