levenshtein, js

gistfile1.txt

function levenshtein (s1, s2) {
    if (s1 == s2) { return 0; }

    if (s1.length === 0 || s2.length===0) { return s2.length+s1.length; }

    var split = false;
    try {
        split = !('0')[0];
    } catch (e) {
        split = true;
    }

    if (split) {
        s1 = s1.split('');
        s2 = s2.split('');
    }

    var v0 = new Array(s1.length + 1);
    var v1 = new Array(s1.length + 1);

    var s1_idx = 0,s2_idx = 0, cost = 0;
    for (s1_idx = 0; s1_idx < s1.length + 1; s1_idx++) { v0[s1_idx] = s1_idx; }
    var char_s1 = '',char_s2 = '';
    for (s2_idx = 1; s2_idx <= s2.length; s2_idx++) {
        v1[0] = s2_idx;
        char_s2 = s2[s2_idx - 1];

        for (s1_idx = 0; s1_idx < s1.length; s1_idx++) {
            char_s1 = s1[s1_idx];
            cost = (char_s1 == char_s2) ? 0 : 1;
            var m_min = v0[s1_idx + 1] + 1;
            var b = v1[s1_idx] + 1;
            var c = v0[s1_idx] + cost;
            if (b < m_min) { m_min = b; }
            if (c < m_min) { m_min = c; }
            v1[s1_idx + 1] = m_min;
        }
        var v_tmp = v0;
        v0 = v1;
        v1 = v_tmp;
    }
    return v0[s1.length];
}