Flatten object into key:value pair.

flatten.js

function flatten(data) {
	let output = {};

	if (!Array.isArray(data) && (!data || typeof data !== 'object' || data.constructor !== Object)) return data;

	for (const key in data) {
		if (Array.isArray(data[key]) || (data[key] && typeof data[key] === 'object' && data[key].constructor === Object)) {
			let returnData = flatten(data[key]);

			for (let returnKey in returnData) {
				output[key + '.' + returnKey] = returnData[returnKey];
			}
		} else {
			output[key] = data[key];
		}
	}

	return output;
}