getLevenshteinDistance.js

function getLevenshteinDistance(a, b) {
    if(a.length === 0) return b.length; 
    if(b.length === 0) return a.length; 
 
    var matrix = [];
 
    var i;
    for(i = 0; i <= b.length; i++){
        matrix[i] = [i];
    }
 
    var j;
    for(j = 0; j <= a.length; j++){
        matrix[0][j] = j;
    }
 
    for(i = 1; i <= b.length; i++){
        for(j = 1; j <= a.length; j++){
            if(b.charAt(i-1) == a.charAt(j-1)){
                matrix[i][j] = matrix[i-1][j-1];
            } else {
                matrix[i][j] = Math.min(matrix[i-1][j-1] + 1,
                                    Math.min(matrix[i][j-1] + 1,
                                        matrix[i-1][j] + 1));
            }
        }
    }
    return matrix[b.length][a.length];
}