function simpleCheck(id)
{
    if ($(id).value && window.trim($(id).value)) {
        $('submit').disabled = false;
    } else {
        $('submit').disabled = true;
    }
}

function checkFeedBack()
{
    if (window.trim($('mail').value) || window.trim($('message').value) || $('file').value) {
        $('submit').disabled = false;
    } else {
        $('submit').disabled = true;
    }
}

function trim(str, charlist)
{
	charlist = !charlist ? ' \s\xA0' : charlist.replace(/([\[\]\(\)\.\?\/\*\{\}\+\$\^\:])/g, '\$1');
	var reg = new RegExp('^[' + charlist + ']+|[' + charlist + ']+$', 'g');
	return str.replace(reg, '');
}

function $(id)
{
    return document.getElementById(id);
}