function isBlank(val){
    if(val==null){return true;}
    for(var i=0;i<val.length;i++) {
        if ((val.charAt(i)!=' ')&&(val.charAt(i)!="\t")&&(val.charAt(i)!="\n")&&(val.charAt(i)!="\r")){return false;}
    }
    return true;
}


function isDigit(num)
{
    if (num.length>1){return false;}
    var string="1234567890";
    if (string.indexOf(num)!=-1){return true;}
    return false;
}

function isInteger(val){
    if (isBlank(val)){return false;}
    for(var i=0;i<val.length;i++){
        if(!isDigit(val.charAt(i))){return false;}
    }
    return true;
}

function checkEmail(email)
{
    var objRegExp = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
    return objRegExp.test(email);
}

function newsletterSend(messageOk, messageError)
{
    var eml = document.getElementById('email-newsletter').value;
    if(!checkEmail(eml)) { eml = ""; }
    if(eml == "")
    {
        alert(messageError);
        return false;
    } else {
        alert(messageOk);
        return true;           
    }
}

function checkRecommendation(messageOk, messageError, labelName) {
    var eml = document.getElementById('email-znamy').value;
    var jmeno = document.getElementById('name').value;
    
    if(jmeno.length < 6) {
        jmeno = '';
    }
    
    if(jmeno == labelName) {
        jmeno = '';
    }
    
    if(!checkEmail(eml)) { eml = ""; }
    if(eml == "" || jmeno == "")
    {
        alert(messageError);
        return false;
    } else {
        alert(messageOk);
        return true;
    }
    
}