As close to actually random selection as I can figure out with JavaScript.

get-random-winner.js

// get the entries into an array
const entries = ['[email protected]', '[email protected]', '[email protected]', '[email protected]'];

function getRandomEntry(entry_array) {
	const NUMBER_OF_ENTRIES = entry_array.length;
	const UINT16_MAX_VALUE = 65_535;
	

	/**
	 * `crypto.getRandomValues()` generates a cryptographically secure random value
	 *
	 * @see https://mdn.io/crypto.getRandomValues
	 */
	const randomNumber = crypto.getRandomValues(new Uint16Array(1)).at(0);
	
	// clamp range to one of the available entry indices
	const winnerIndex = Math.floor(randomNumber / ((UINT16_MAX_VALUE + 1) / NUMBER_OF_ENTRIES));
	const winner = entry_array.at(winnerIndex);

	return winner;
}

console.log({ winner: getRandomEntry(entries) });