Levenshtein (edit) Distance in JS

Levenshtein.js

function getDistance(strA, strB) {
  const matrix = [];
  
  const arrA = strA.split('');
  const arrB = strB.split('');
  
  // fill matrix with a row for each character and
  // for each row add a single column with incrementing (0 to length)
  for(let a = 0; a < arrA.length + 1; a++) {
    matrix[a] = [a]  
  }
  
  // fill first row with column for each character incrementing (0 to length)
  for(let b = 0; b < arrB.length + 1; b++) {
    matrix[0][b] = b
  }
  
  // Iterate through each unit in the matrix starting at the second row / second column
  for(let a = 1; a < arrA.length + 1; a++) {
    for(let b = 1; b < arrB.length + 1; b++) {
    
      // calculate minimum of left unit, left diaganol unit and above unit
      let min = Math.min(
        matrix[a - 1][b - 1],
        Math.min(
          matrix[a - 1][b],
          matrix[a][b - 1]
        )
      )
      
      // if the two characters match, there is no cost,
      // otherwise one operation has cost of 1
      matrix[a][b] = min + (arrA[a - 1] === arrB[b - 1] ? 0 : 1)
    }
  }
  
  return matrix[arrA.length][arrB.length];
}