A simple function that lets you access complex object properties with the use of a single string Raw

propertyByString.ts

const countries = [
	{
		country: {
			name: 'Greece',
			id: 1,
			people: [
				[1, 2, 3],
				[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
				[
					['alice'],
					['john'],
					{
						test: [
							['deep']
						]
					}
				]
			]
		}
	}
];

const publishers = {
	languages: [
		'greek',
		'english',
		{ dialect: ['one', 'two'] }
	]
};

console.log('Access array without name: ', propertyByString(countries, '$0.country.name'));
// "Access array without name: ",  "Greece" 
console.log('Access array of object: ', propertyByString(publishers, 'languages$0'));
// "Access array of object: ",  "greek"
console.log('Access object inside of array: ', propertyByString(publishers, 'languages$2.dialect$1'));
// "Access array of object: ",  "greek"
console.log('Access 2d-array inside of array of object: ', propertyByString(countries, '$0.country.people$1$11'));
// "Access 2d-array inside of array of object: ",  11 
console.log('An extreme example: ', propertyByString(countries, '$0.country.people$2$2.test$0$0'));
// "An extreme example: ",  "deep" 
console.log('If something is wrong null is returned: ', propertyByString(countries, '$a.name'));
// "If something is wrong null is returned: ",  null 
console.log('If something is wrong null is returned: ', propertyByString(countries, '$0.name'));
// "If something is wrong null is returned: ",  null 


function propertyByString(obj: any, path: string): any | null {
	if (!obj || !path) return null;

	const properties = path.split('.');
	let prop: any = obj;
	for (let i = 0; i < properties.length; i++) {
		const array_prop = propByArray(prop, properties[i]);
		if (!array_prop) {
			prop = prop[properties[i]];
			if (!prop)
				return null;
		} else {
			prop = array_prop;
		}

	}

	return prop;
}

function propByArray(obj: any, path: string): any | null {
	const array_property = path.split('$');

	if (array_property.length === 0)
		return null;
	if (array_property[0] !== '')
		obj = obj[array_property[0]];
	if (!obj)
		return null;

	let array_property_number = []
	for (let i = 1; i < array_property.length; i++) {
		const index_cancdidate = +array_property[i];
		if (typeof index_cancdidate === "number")
			array_property_number.push(index_cancdidate);
		else
			return null;
	}

	for (let i = 0; i < array_property_number.length; i++) {
		obj = obj[array_property_number[i]];
		if (!obj)
			return null;
	}

	return obj;
}

Nice job!