reselect-equality-check-n-parameters

A simple memoize factory function that only checks equality on the first n parameters

To be used as an extension to the reselect library.

Install:

npm install reselect-equality-check-n-parameters --save

Example:

    import { createSelectorCreator } from 'reselect';
    import { equalityCheckNParamsCreator } from 'reselect-equality-check-n-parameters';
    
    // This creates a memoize function that will only check the first parameter
    const equalityCheckFirstParam = equalityCheckNParamsCreator(1);

    // Import createSelectorCreator from the reselect library passing it the memoize function
    const createSelectorFirstParam = createSelectorCreator(equalityCheckFirstParam);

    const selector = createSelectorFirstParam(
        state => state.a,
        state => state.b,
        (a, b) => a + b
    );

    const state1 = {a: 1, b: 2};
    selector(state1); // would be 3
    
    // "b" will not be checked for equality
    // even if it has changed, no new value will be calculated
    const state2 = {a: 1, b: 4};
    selector(state2) // would be 3
    selector.recomputations() // would be 1
    
    const state3 = {a: 2, b: 4};
    selector(state3) // would be 6 as "a" has changed

NPM tasks

• npm test runs the tests via karma
• npm build builds a UMD version for distribution with webpack
• npm pre-publish used when publishing to NPM

Publishing checklist

1. Run tests npm test
2. Run build and check that your module was built (needs to be exported via index.ts to index.js)
3. Install it into your project to test before publishing by running npm install '/path-to-this/'
4. Bump version in package.json following Semantic Versioning SemVer
5. Tag the release commit in git: git tag -a v0.1.5 -m "Published v0.1.5"
6. Push the tags up to github: git push origin --tags
7. Publish npm publish