stringSimilarity.js

/**
 * This method uses the Jaro similarity algorithm to measure the similarity between two strings (words or phrases).
 * Adapted from https://www.geeksforgeeks.org/jaro-and-jaro-winkler-similarity/
 * @author 5antos#4876
 * @param {string} str1 First string
 * @param {string} str2 Second string
 * @returns {number} Number between 0 and 1, where 1 means the strings are equal and 0 means no similarity between the strings
 */

function checkSimilarity(str1, str2) {
  if (str1 === str2) return 1.0

  const len1 = str1.length
  const len2 = str2.length

  const maxDist = ~~(Math.max(len1, len2)/2)-1
  let matches = 0

  const hash1 = []
  const hash2 = []

  for(var i=0; i<len1; i++)
    for(var j=Math.max(0, i-maxDist); j<Math.min(len2, i+maxDist+1); j++)
      if (str1.charAt(i) === str2.charAt(j) && !hash2[j]) {
        hash1[i]=1
        hash2[j]=1
        matches++
        break
      }

  if (!matches) return 0.0

  let t = 0
  let point = 0

  for(var k=0; k<len1; k++)
    if (hash1[k]) {
      while(!hash2[point])
        point++

      if (str1.charAt(k) !== str2.charAt(point++))
        t++
    }

  t/=2

  return ( (matches/len1) + (matches/len2) + ((matches-t)/matches) )/3.0
}


// Example Outputs:

checkSimilarity('arnab', 'raanb') // ~0.86667
checkSimilarity('CRATE', 'TRACE') // ~0.73334
checkSimilarity('DwAyNE', 'DuANE') // ~0.82223