function EmailChecker_getFocus(){
    this.email_obj.focus();
}

function EmailChecker(email_obj)
{
    this.email_obj = email_obj;
    email_str = email_obj.value;
    
  
    
    this.focus = EmailChecker_getFocus;
    
    this.error_id = 0;
    
    error_messages = new Array();
    
    error_messages[0] = 0;
    error_messages[1] = "Email address is blank.";
    error_messages[2] = "Email address does not contain the '@' symbol";
    error_messages[3] = "Email address contains the '@' symbol more than once";
    error_messages[4] = "Email address cannot end with the '@' symbol";
    error_messages[5] = "Email address cannot start with the '@' symbol";
    error_messages[6] = "Email address cannot contain the symbol pairs '.@', '..' or '@.'";
    error_messages[7] = "Email address must contain an '.' symbol";
    error_messages[8] = "Email address cannot end with the '.' symbol";
    error_messages[9] = "Email address cannot start with the '.' symbol";
    error_messages[10] = "Email address contains an invalid symbol";
    
    if(email_str == ''){
        this.error_id = 1;
    }
    else if(email_str.indexOf("@") == -1){
        this.error_id = 2;
    }
    else if(email_str.split("@").length > 2){
        this.error_id = 3;
    }
    else if(email_str.charAt( (email_str.length - 1) ) == "@"){
        this.error_id = 4;
    }
    else if(email_str.charAt(0) == "@"){
        this.error_id = 5;
    }
    else if(email_str.indexOf(".@") >=0 | email_str.indexOf("..") >=0 | email_str.indexOf("@.") >=0 ){
        this.error_id = 6;
    }
    else if(email_str.indexOf(".") == -1){
        this.error_id = 7;
    }
    else if(email_str.charAt( (email_str.length - 1) ) == "."){
        this.error_id = 8;
    }
    else if(email_str.charAt(0) == "."){
        this.error_id = 9;
    }
    
    if (this.error_id == 0){
        var regex = /^([a-zA-Z0-9_\-])+([a-zA-Z0-9_\.\-])*\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9])+$/;
        var found_regex = regex.exec(email_str);
    
        if(found_regex == null){
        	this.error_id = 10;
        }
    } //end if this.error_id == 0
    
    this.error_msg = error_messages[this.error_id];
    
} //end EmailChecker()