localStorage test

var storageKey = 'superzero';
var from = 50;
var to = 100;
var expire = 30;
var data = localStorage.getItem(storageKey);
var bSave = false;
var gen;
if (data != null) {
    data = JSON.parse(data);

    if (data.value !== undefined) {
        gen = data.value;
    }

    if (data.timestamp !== undefined) {
        var now = new Date().getTime();

        var diff = now - data.timestamp;

        if (diff > (expire * 60 * 1000)) {
            bSave = true;
        }
    }
}
else {
    bSave = true;
}

if (bSave) {
    gen = Math.floor(Math.random()*(to-from+1)+from);
    var data = {
        value: gen,
        timestamp: new Date().getTime()
    };
    localStorage.setItem(storageKey, JSON.stringify(data));
}

if (gen != null) {
    document.writeln(gen);
}