Discussion on: Daily Challenge #8 - Scrabble Word Calculator

[Alvaro Montoro]

JavaScript

const scrabbleWordValue = word => {

  // scrabble letter values
  const letterValues = { a:1, b:3, c:3, d:2, e:1, f:4, g:2, 
                         h:4, i:1, j:8, k:5, l:1, m:3, n:1, 
                         o:1, p:3, q:10, r:1, s:1, t:1, u:1, 
                         v:4, w:4, x:8, y:4, z:10 };

  // Pre-requesites - check that the string fulfills a good pattern:
  //   - it must start with a letter
  //   - followed by have any combination of letters and asterisks
  //   - optionally at the end it can have a (t) or (d) modifier
  // if it doesn't follow that pattern (invalid or empty), return 0 points
  if(!word.match(/^([a-z][\*]{0,2})+(\([t|d]\))?$/gi)) {
    return 0;
  }

  // word modifier - calculate the multiplier that will apply to the word:
  //   - 1 (default): the word will not change value
  //   - 2 (if it ends with '(d)'): the word will be multiplied by 2
  //   - 3 (if it ends with '(t)'): the word will be multiplied by 3
  // after calculating the word multiplier, update the word id applicable.
  let wordModifier = 1;
  if (word.indexOf("(") > 0) {
    wordModifier = word.indexOf("(t)") > 0 ? 3 : 2;
    word = word.slice(0,-3);
  }

  // calculate the addition of all letters
  //   - if the letter is an asterisk, use the previous letter
  //   - update the previous letter to current letter
  //   - add the value of the letter to the total
  let previous = 0;
  let valueWord = word.split('')
                      .reduce((acc, curr) => {
                        if (curr == '*') curr = previous;
                        previous = curr;
                        return letterValues[curr] + acc;
                      }, 0);

  // if the words has seven letters, add 50 extra points!
  const allLettersBonus = word.replace(/\*/g,'').length == 7 ? 50 : 0;

  // return the value of the word considering all modifiers
  return valueWord * wordModifier + allLettersBonus;
}

Live demo on CodePen.