similarity.js

// String similarity comparison
// ES Module wrapper

function compareTwoStrings(first, second) {
  first = first.replace(/\s+/g, "");
  second = second.replace(/\s+/g, "");

  if (first === second) return 1;
  if (first.length < 2 || second.length < 2) return 0;

  let firstBigrams = new Map();
  for (let i = 0; i < first.length - 1; i++) {
    const bigram = first.substring(i, i + 2);
    const count = firstBigrams.has(bigram) ? firstBigrams.get(bigram) + 1 : 1;
    firstBigrams.set(bigram, count);
  }

  let intersectionSize = 0;
  for (let i = 0; i < second.length - 1; i++) {
    const bigram = second.substring(i, i + 2);
    const count = firstBigrams.has(bigram) ? firstBigrams.get(bigram) : 0;
    if (count > 0) {
      firstBigrams.set(bigram, count - 1);
      intersectionSize++;
    }
  }

  return (2.0 * intersectionSize) / (first.length + second.length - 2);
}

export const stringSimilarity = {
  compareTwoStrings
};