function IsEmpty( text )
{
    if( text.value.length == 0 ) 
        return( true );
    for( var i=0; i<text.value.length; ++i )  
    {
        var ch = text.value.charAt(i);
        if( ch != ' ' && ch != '\t' ) 
            return( false );
    }
    return( true );
}


function IsEmail( text )
{
    if( text.value.length == 0 ) 
        return( false );
    if( text.value.indexOf("@") == -1 || text.value.indexOf(".") == -1 )
        return( false );
    return( true );
}


function validateForm(f){
	 if (IsEmpty(f.email) || !IsEmail(f.email)){
		alert("Please enter a valid e-mail address.");
		f.email.focus();
	} else if(IsEmpty(f.zip)){
		alert("Please provide your zip code.");
		f.zip.focus();
	}else return true;
	return false;
}