function trim(str)
{
     return str.replace(/^\s*|\s*$/g, "");
}

function isUrl(s)
{
    var regexp = /(http|https):\/\/(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?/
    return regexp.test(s);
}

function validateForm()
{
    var err = '';
    var is_first = true;

    var title = document.getElementById('title');
    if (trim(title.value).length == 0) {
        if (is_first) {
            title.focus();
            is_first = false;
        }
        err += "Title shouldn't be empty!\n";
    }

    var url = document.getElementById('url');
    if (!isUrl(url.value)) {
        if (is_first) {
            url.focus();
            is_first = false;
        }
        err += "URL should be valid!\n";
    }

    if (err.length > 0) {
        alert(err);
        return false;
    }

    return true;
}