RWC Wordle Validation

wordle-validation.js

const CORRECT = 'correct';
const OUT_OF_PLACE = 'out of place';
const WRONG = 'wrong';

/**
 * Determines which letters in a given guess are correct, which ones are out of place, and which ones are invalid and returns emoji string
 * @param {string} guess five-letter guess (presumes the guess has already been through other formatting validations like length and valid characters)
 * @param {string} solution the target word the player is trying to guess
 * @returns {string} emoji sequence
 */
function validateWordleGuess(guess, solution) {
	/**
	 * @type {{letter: string, state: CORRECT | OUT_OF_PLACE | WRONG}[]}
	 */
	const guessedLetters = guess
		.split('')
		.map(letter => ({letter, state: WRONG}));

	/**
	 * @type {{letter: string, includedInGuess: boolean}[]}
	 */
	const solutionLetters = solution
		.split('')
		.map(letter => ({letter, includedInGuess: false}));

	// First pass: correct letters in the correct place
	for (let i = 0; i < guessedLetters.length; i++) {
		if (guessedLetters[i].letter === solutionLetters[i].letter) {
			guessedLetters[i].state = CORRECT;
			solutionLetters[i].includedInGuess = true;
		}
	}

	// Second pass: correct letters in the wrong places
	for (let i = 0; i < guessedLetters.length; i++) {
		if (guessedLetters[i].state === CORRECT) {
			continue;
		}

		const letterFoundElsewhere = solutionLetters
			.find((solutionLetter) => {
				const matchesLetter = solutionLetter.letter === guessedLetters[i].letter;
				return matchesLetter && !solutionLetter.includedInGuess;
			});

		if (letterFoundElsewhere) {
			guessedLetters[i].state = OUT_OF_PLACE;
			letterFoundElsewhere.includedInGuess = true;
		}
	}

	const emojis = guessedLetters.map(guessedLetter => {
		switch (guessedLetter.state) {
			case CORRECT:
				return '🟩';
			case OUT_OF_PLACE:
				return '🟨';
			case WRONG:
			default:
				return '⬛';
		}
	});

	return emojis.join('');
}

console.log(validateWordleGuess('reads', 'fudge'));
console.log(validateWordleGuess('lodge', 'fudge'));