@augment-vir/common/dist/augments/object/merge-deep.js

A collection of augments, helpers types, functions, and classes for any JavaScript environment.

import { check } from '@augment-vir/assert';
/**
 * Accepts multiple objects and merges their key-value pairs recursively. Any values set to
 * undefined will be removed.
 *
 * Note that order matters! Each input object will overwrite the properties of the previous objects.
 *
 * @category Object : Merge
 * @category Package : @augment-vir/common
 * @package [`@augment-vir/common`](https://www.npmjs.com/package/@augment-vir/common)
 */
export function mergeDeep(...inputs) {
    if (!check.isLengthAtLeast(inputs, 1)) {
        // nothing to merge if no inputs
        return {};
    }
    if (inputs.length === 1) {
        // nothing to merge if only one input
        return inputs[0];
    }
    let result = undefined;
    const mergeProps = {};
    inputs.forEach((individualInput) => {
        if (!check.isObject(individualInput)) {
            /** If not an object, we can't merge. So overwrite instead. */
            result = individualInput;
            return;
        }
        else if (!check.isObject(result)) {
            /** If result isn't an object then we need to make it into one. */
            result = { ...individualInput };
        }
        Object.entries(individualInput).forEach(([key, value,]) => {
            if (!mergeProps[key]) {
                mergeProps[key] = [];
            }
            mergeProps[key].push(value);
        });
    });
    if (check.isObject(result)) {
        Object.entries(mergeProps).forEach(([key, mergeValues,]) => {
            const newValue = mergeDeep(...mergeValues);
            if (newValue === undefined && key in result) {
                delete result[key];
            }
            else if (newValue !== undefined) {
                result[key] = newValue;
            }
        });
    }
    return result;
}