function sendForm(formName, field, value){
    document.forms[formName][field].value = value;
    document.forms[formName].submit();
}

function showImageDiv(divId, image){
    element = document.getElementById(divId);
    element.innerHTML = '<img src="' + image + '" border=0>';
}

function copyInnerHTML(tagFrom, tagTo){
    //first hide all
    var elementSrc = document.getElementById(tagFrom);
    var elementDst = document.getElementById(tagTo);
    //copy content
    elementDst.innerHTML = elementSrc.innerHTML;
}


//function that counts total cost
function valueChanged(numberOfFields, fieldPrefix1, fieldPrefix2, outputSuffix){
    var totalBudget  = 0;
    var totalSpent   = 0;
    var error1       = false;
    var error2       = false;
    var fieldTmp     = null;

    for( var i=0; i<numberOfFields; i++){
        var fieldTmp = document.getElementById(fieldPrefix1 + i);
        if( isNaN(fieldTmp.value) ){
            error1 = true;
        }
        totalBudget += Math.ceil(fieldTmp.value);       

        var fieldTmp = document.getElementById(fieldPrefix2 + i);
        if( isNaN(fieldTmp.value) ){
            error2 = true;
        }
        totalSpent += Math.ceil(fieldTmp.value);       
    }

    fieldTmp = document.getElementById(fieldPrefix1 + outputSuffix);
    if(error1 == true){
        fieldTmp.innerHTML = 'Incorrect value.';
    }else{
        fieldTmp.innerHTML = totalBudget;
    }

    fieldTmp = document.getElementById(fieldPrefix2 + outputSuffix);
    if(error2 == true){
        fieldTmp.innerHTML = 'Incorrect value.';
    }else{
        fieldTmp.innerHTML = totalSpent;
    }

    fieldTmp = document.getElementById(fieldPrefix1 + fieldPrefix2 + outputSuffix);
    if( error1 == true || error2 == true){
        fieldTmp.innerHTML = 'Incorrect value.';
    }else{
        fieldTmp.innerHTML = totalBudget-totalSpent;
    }

    if(error1 == true || error2 == true){
        alert('Please enter only positive integer numbers.');
        return 'error';
    }


    if(error1 == true || error2 == true){
        alert('Please enter only positive integer numbers.');
        return 'error';
    }
  
    return true;
}