kalman-filter/lib/utils/deep-assign.js

Kalman filter (and Extended Kalman Filter) Multi-dimensional implementation in Javascript

const uniq = require('./uniq.js');

const limit = 100;

/**
*Equivalent to the Object.assign method, takes several arguments and creates a new object corresponding to the assignment of the arguments
* @param {Object} args
* @param {Number} step
* @returns {Object}
*/
const deepAssign = function (args, step) {
	if (step > limit) {
		throw (new Error(`In deepAssign, number of recursive call (${step}) reached limit (${limit}), deepAssign is not working on  self-referencing objects`));
	}

	const filterArguments = args.filter(arg => (arg) !== undefined && arg !== null);
	const lastArgument = filterArguments[filterArguments.length - 1];
	if (filterArguments.length === 1) {
		return filterArguments[0];
	}

	if (typeof (lastArgument) !== 'object' || Array.isArray(lastArgument)) {
		return lastArgument;
	}

	if (filterArguments.length === 0) {
		return null;
	}

	const objectsArguments = filterArguments.filter(arg => typeof (arg) === 'object');
	let keys = [];
	for (const arg of objectsArguments) {
		keys = keys.concat(Object.keys(arg));
	}

	const uniqKeys = uniq(keys);
	const result = {};
	for (const key of uniqKeys) {
		const values = objectsArguments.map(arg => arg[key]);
		result[key] = deepAssign(values, step + 1);
	}

	return result;
};

module.exports = ((...args) => deepAssign(args, 0));