article-parser/src/bun/string-similarity.js

To extract main article from given URL

/**
 * Based on string-similarity by aceakash
 * Original: https://github.com/aceakash/string-similarity
 * Convert to es6 module syntax to fix error on bun.js
**/

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

const compareTwoStrings = (first, second) => {
  first = first.replace(/\s+/g, '')
  second = second.replace(/\s+/g, '')

  if (first === second) return 1 // identical or empty
  if (first.length < 2 || second.length < 2) return 0 // if either is a 0-letter or 1-letter string

  const 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 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 }
}