nearAPI.js

// Copyright 2018-2022 BadAimWeeb. All rights reserved. MIT license.

function compareTwoStrings(first, second) {
  first = first.replace(/\s+/g, '')
  second = second.replace(/\s+/g, '')
  if (!first.length && !second.length) return 1;                   // if both are empty strings
  if (!first.length || !second.length) return 0;                   // if only one is empty string
  if (first === second) return 1;                      // identical
  if (first.length === 1 && second.length === 1) return 0;         // both are 1-letter strings
  if (first.length < 2 || second.length < 2) return 0;       // if either is a 1-letter string
  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);
}

function findBestMatch(mainString, targetStrings) {
  if (!areArgsValid(mainString, targetStrings)) throw new Error('Bad arguments: First argument should be a string, second should be an array of strings');
  const ratings = [];
  let bestMatchIndex = 0;
  for (let i = 0; i < targetStrings.length; i++) {
    const currentTargetString = targetStrings[i];
    const currentRating = compareTwoStrings(mainString, currentTargetString)
    ratings.push({
      target: currentTargetString, 
      rating: currentRating
    });
    if (currentRating > ratings[bestMatchIndex].rating) {
      bestMatchIndex = i
    }
  }
  const bestMatch = ratings[bestMatchIndex]
  return { 
    ratings, 
    bestMatch, 
    bestMatchIndex 
  };
}

function areArgsValid(mainString, targetStrings) {
  if (typeof mainString !== 'string') return false;
  if (!Array.isArray(targetStrings)) return false;
  if (!targetStrings.length) return false;
  if (targetStrings.find(s => typeof s !== 'string')) return false;
  return true;
}

module.exports = {
  findBestMatch,
  compareTwoStrings
}