Levenshtein Distance in JavaScript

Levenshtein Distance

The Levenshtein distance is a string metric for measuring the difference between two sequences. It is the minimum number of single-character edits required to change one word into the other.

For example −

Consider, we have these two strings −

const str1 = 'hitting';
const str2 = 'kitten';

The Levenshtein distance between these two strings is 3 because we are required to make these three edits −

• kitten → hitten (substitution of "h" for "k")

• hitten → hittin (substitution of "i" for "e")

• hittin → hitting (insertion of "g" at the end)

We are required to write a JavaScript function that takes in two strings and calculates the Levenshtein distance between them.

Example

Following is the code −

const str1 = 'hitting';
const str2 = 'kitten';
const levenshteinDistance = (str1 = '', str2 = '') => {
   const track = Array(str2.length + 1).fill(null).map(() =>
   Array(str1.length + 1).fill(null));
   for (let i = 0; i <= str1.length; i += 1) {
      track[0][i] = i;
   }
   for (let j = 0; j <= str2.length; j += 1) {
      track[j][0] = j;
   }
   for (let j = 1; j <= str2.length; j += 1) {
      for (let i = 1; i <= str1.length; i += 1) {
         const indicator = str1[i - 1] === str2[j - 1] ? 0 : 1;
         track[j][i] = Math.min(
            track[j][i - 1] + 1, // deletion
            track[j - 1][i] + 1, // insertion
            track[j - 1][i - 1] + indicator, // substitution
         );
      }
   }
   return track[str2.length][str1.length];
};
console.log(levenshteinDistance(str1, str2));

Output

Following is the output on console −

3