Package Exports
- memoize-one
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Readme
memoizeOne
A simple memoization library which only remembers the latest invokation
DOCS: Work in progress
Rationale
Cache invalidation is hard:
There are only two hard things in Computer Science: cache invalidation and naming things.
Phil Karlton
So keep things simple and just use a cache size of one.
Unlike other memoization libraries, memoizeOne only remembers the latest arguments. No need to worry about cache busting mechanisms such as maxAge, maxSize, exlusions and so on which can be prone to memory leaks. memoizeOne simply remembers the last arguments, and if the function is next called with the same arguments then it returns the previous result.
Usage
Standard usage
import memoizeOne from 'memoize-one';
const add = (a, b) => a + b;
const memoizedAdd = memoizeOne(add);
memoizedAdd(1, 2); // 3
memoizedAdd(1, 2); // 3
// Add function is not executed: previous result is returned
memoizedAdd(2, 3); // 5
// Add function is called to get new value
memoizedAdd(2, 3); // 5
// Add function is not executed: previous result is returned
memoizedAdd(1, 2); // 3
// Add function is called to get new value.
// While this was previously cached,
// it is not the latest so the cached result is lostCustom equality function
You can also pass in a custom function for checking the equality of two items.
import memoizeOne from 'memoize-one';
import deepEqual from 'lodash.isEqual';
const identity = x => x;
const defaultMemoization = memoizeOne(identity);
const customMemoization = memoizeOne(identity, deepEqual);
const result1 = defaultMemoization({foo: 'bar'});
const result2 = defaultMemoization({foo: 'bar'});
result1 === result2 // false - difference reference
const result3 = customMemoization({foo: 'bar'});
const result4 = customMemoization({foo: 'bar'});
result3 === result4 // true - arguments are deep equalInstallation
# yarn
yarn add memoize-one
# npm
npm install memoize-one --saveOther features
Correctly supports this binding
Custom equality function
Code health
- Tested with all JavaScript types
- 100% code coverage
- flow types for safer internal execution and type checking / auto complete for editors
- Semantically versioning (2.0)