function isBlank(name)
{
    
    
     var obj = document.getElementById(name);    

    if(!obj.value) 
     { 
           return true;
      }

    
    if(obj.value.length == 0)
     {
       return true;
      }
    
    return false;
}


function validateForm()
{
    var errors = "";
    
    if(isBlank("Name")) { errors += "Name field required\n"; }

    if(isBlank("Telephone"))
    { errors += "Telephone required\n"; }
    else
    {
        var phonenumber = document.getElementById("Telephone");
        var num = phonenumber.value;
        num = num.replace(/ /, '');
        if(isNaN(num)) { errors += "Invalid telephone number\n"; }
    }
    
    if(isBlank("Email")) { errors += "Email required\n"; }
    else
    {
        var email = document.getElementById("Email");
        email = email.value;
        var p = email.indexOf('@');
        if(p < 1 || p == (email.length - 1)) { errors += "Invalid email\n"; }
    }
    
    if(isBlank("Postcode"))    { errors += "Postcode required\n"; }
    if(isBlank("Description"))    { errors += "Description required\n"; }
    
    if(errors != '')
    { alert(errors); }
    
    document.validate_ret = (errors == '');
    
}