array diff

arrayDiff.js

Array.diff = function(left, right)
{
    var o = left;
    var n = right;

    var ns = {};
    var os = {};

    for (var i = 0; i < n.length; i++) {
        if (ns[n[i]] == null)
            ns[n[i]] = { rows: [], o: null };
        ns[n[i]].rows.push(i);
    }

    for (var i = 0; i < o.length; i++) {
        if (os[o[i]] == null)
            os[o[i]] = { rows: [], n: null };
        os[o[i]].rows.push(i);
    }

    for (var i in ns) {
        if (ns[i].rows.length == 1 && typeof(os[i]) != "undefined" && os[i].rows.length == 1) {
            n[ns[i].rows[0]] = { text: n[ns[i].rows[0]], row: os[i].rows[0] };
            o[os[i].rows[0]] = { text: o[os[i].rows[0]], row: ns[i].rows[0] };
        }
    }

    for (var i = 0; i < n.length - 1; i++) {
        if (n[i].text != null && n[i + 1].text == null && n[i].row + 1 < o.length && o[n[i].row + 1].text == null && n[i + 1] == o[n[i].row + 1]) {
            n[i + 1] = { text: n[i + 1], row: n[i].row + 1 };
            o[n[i].row + 1] = { text: o[n[i].row + 1], row: i + 1 };
        }
    }

    for (var i = n.length - 1; i > 0; i--) {
        if (n[i].text != null && n[i - 1].text == null && n[i].row > 0 && o[n[i].row - 1].text == null && 
            n[i - 1] == o[n[i].row - 1]) {
            n[i - 1] = { text: n[i - 1], row: n[i].row - 1 };
            o[n[i].row - 1] = { text: o[n[i].row - 1], row: i - 1 };
        }
    }

    return { left: o, right: n };
}