merge-extends v1.1.0

merge-extends.js

walk the extend(s) property of an object, returning a single merged object

Usage

import { mergeExtends, merger } from 'merge-extends';

const objects = new Map();

const getter = (id) => objects.get(id);

// you can just pass an identifier if you like
objects.set('abc', { abc: 123 });
mergeExtends('abc', getter); // { abc: 123 }

// or you can pass a whole source object
objects.set('def', { def: 456 });
mergeExtends({ lmn: 345, extend: 'def' }, getter); // { def: 456, lmn: 345 }

// you can conveniently use the same getter over and over
const objectsMerger = merger(getter);
objects.set('ghi', { ghi: 789, extend: 'def' });
objectsMerger('ghi'); // { def: 456, ghi: 789 }

// we also support an array of extends
objects.set('jki', { jki: 1012, extends: ['abc', 'ghi'] });
objectsMerger('jki'); // { abc: 123, def: 456, ghi: 789, jki: 1012 }

// an optional customiser can be used to implement deep merging
const concatArrays = (targetValue, sourceValue) => {
  return Array.isArray(targetValue) ? targetValue.concat(sourceValue) : sourceValue;
};
const customObjectsMerger = merger(getter, concatArrays);
objects.set('birds', { names: [ 'canary' ] });
objects.set('fish', { names: [ 'sardine' ] });
objects.set('fauna', { extends: [ 'birds', 'fish' ] });
customObjectsMerger('fauna'); // { names: [ 'canary', 'sardine' ] }

API

mergeExtends(source, getter, customiser)

• @param {Object|String} source
• @param {Function} getter
• @param {Function} customiser
• @returns {Object}

Like lodash.assign(), we invoke the optional customiser function with five arguments: (targetValue, sourceValue, key, target, source).

merger(getter, customiser)

• @param {Function} getter
• @param {Function} customiser
• @returns {Function}