es-next-tools/dist/object/mergeDeep.js

A comprehensive utility library for JavaScript and TypeScript that provides a wide range of functions for common programming tasks, including mathematical operations, date manipulations, array and object handling, string utilities, and more.

/**
 * Deeply merges multiple objects into a target object.
 * @param {T} target - The target object to merge into.
 * @param {...Partial<S>[]} sources - The source objects to merge from.
 * @returns The merged object.
 * @example
 * const obj1 = { a: { b: 2 }, c: 3 };
 * const obj2 = { a: { d: 4 }, e: 5 };
 * const merged = mergeDeep(obj1, obj2);
 * // { a: { b: 2, d: 4 }, c: 3, e: 5 }
 */
export function mergeDeep(target, ...sources) {
    const output = { ...target };
    if (!sources.length)
        return target;
    const source = sources.shift();
    if (source && typeof output === 'object' && typeof source === 'object') {
        for (const key in source) {
            if (typeof source[key] === 'object' && source[key] !== null) {
                if (!(key in output)) {
                    Object.assign(output, { [key]: source[key] });
                }
                else {
                    output[key] = mergeDeep(output[key], source[key]);
                }
            }
            else {
                Object.assign(output, { [key]: source[key] });
            }
        }
    }
    return sources.length
        ? mergeDeep(output, ...sources) : output;
}