// ------------------------------------------
function enableSubmit()
{
    if (trim(document.getElementById('txtName').value) && isValidEmail(document.getElementById('txtEmail').value) && trim(document.getElementById('txtSubject').value) && trim(document.getElementById('txtMessage').value)) { document.getElementById('btnSend').disabled = false; }
    else { document.getElementById('btnSend').disabled = true; }
}

// Misc and useful

// ------------------------------------------
function isValidEmail(email)
{
	var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
	if (email.match(emailExp)) { return true; }
	else { return false; }
}

// ------------------------------------------
function trim(str)
{
    var result = str.replace(/^\s+|\s+$/g, '');
    return result;
}