javascript version id comparison

version-check.js

// compare two versions, return true if local is up to date, false otherwise
// if both versions are in the form of major[.minor][.patch] then the comparison parses and compares as such
// otherwise the versions are treated as strings and normal string compare is done
var VPAT = /^\d+(\.\d+){0,2}$/;

function upToDate(local, remote) {
    if (!local || !remote || local.length === 0 || remote.length === 0)
        return false;
    if (local == remote)
        return true;
    if (VPAT.test(local) && VPAT.test(remote)) {
        var lparts = local.split('.');
        while(lparts.length < 3)
            lparts.push("0");
        var rparts = remote.split('.');
        while (rparts.length < 3)
            rparts.push("0");
        for (var i=0; i<3; i++) {
            var l = parseInt(lparts[i], 10);
            var r = parseInt(rparts[i], 10);
            if (l === r)
                continue;
            return l > r;
        }
        return true;
    } else {
        return local >= remote;
    }
}