wordle.ts

type LetterGuess = {
  letter: string;
  color: "gray" | "yellow" | "green";
};

let guess = "...";
let target = "...";

// Store the color alongside each guess letter
let guessLetters: LetterGuess[] = guess.split("").map((letter) => ({
  letter,
  color: "gray",
}));

// Store the target in an array of nullables
let targetLetters: (string | null)[] = [...target];

// First pass: match green letters
guessLetters = guessLetters.map(({ letter, color }, index) => {
  // green letters are matched by the specific index in the target
  if (letter === targetLetters[index]) {
    // remove matching green letters from the pool
    // so that they aren't also matched as yellows
    targetLetters[index] = null;
    return { letter, color: "green" };
  } else {
    return { letter, color };
  }
});

// Second pass: greedily match yellow letters
guessLetters = guessLetters.map(({ letter, color }) => {
  if (color === "green") {
    // don't modify existing green letters
    return { letter, color };
  }
  // yellow letters are matched by searching the entire target word
  else if (color === "gray" && targetLetters.includes(letter)) {
    // remove yellow letters once matched,
    // each letter only matches once
    targetLetters[targetLetters.indexOf(letter)] = null;
    return { letter, color: "yellow" };
  } else {
    return { letter, color };
  }
});