deep merge

gistfile1.txt

/**
 * Simple object check.
 * @param item
 * @returns {boolean}
 */
export function isObject(item) {
	return item && typeof item === 'object' && !Array.isArray(item);
}

/**
 * Deep merge two objects.
 * @param target
 * @param ...sources
 */
export function mergeDeep(target, ...sources) {
	if (!sources.length) return target;
	const source = sources.shift();

	if (isObject(target) && isObject(source)) {
		for (const key in source) {
			if (isObject(source[key])) {
				if (!target[key]) Object.assign(target, {[key]: {}});
				mergeDeep(target[key], source[key]);
			} else {
				Object.assign(target, {[key]: source[key]});
			}
		}
	}

	return mergeDeep(target, ...sources);
}