levenshtein.js

// Based off https://en.wikipedia.org/wiki/Levenshtein_distance
// No optimization, really.
function levenshtein(a, b) {
    /* base case: empty strings */
    if (a.length == 0) {
        return b.length;
    }
    if (b.length == 0) {
        return a.length;
    }
    // Test if last characters of the strings match.
    const cost = a[a.length - 1] == b[b.length - 1] ? 0 : 1;
    /* return minimum of delete char from s, delete char from t, and delete char from both */
    return Math.min(levenshtein(a.slice(0, -1), b) + 1, levenshtein(a, b.slice(0, -1)) + 1, levenshtein(a.slice(0, -1), b.slice(0, -1)) + cost);
}