function isEmpty(field,comment) {
        var inputStr = field.value
        if (inputStr == "" || inputStr == null) {
                alert(comment+" field is empty!")
                field.focus()
                field.select()
                return false
        }
        return true
}

function isNumber(field,comment) {
    if (isEmpty(field,comment)) {
        var inputStr = field.value
        for (var i = 0; i < inputStr.length; i++) {
             var oneChar = inputStr.substring(i, i + 1)
             if (oneChar < "0" || oneChar > "9") {
                 alert(comment+" field requires digit!")
                 field.focus()
                 field.select()
                 return false
             }
        }
        return true
    }
    return false
}

function check_email(e) {
        ok = "1234567890qwertyuiop[]asdfghjklzxcvbnm.@-_QWERTYUIOPASDFGHJKLZXCVBNM";

        for(i=0; i < e.length ;i++){
                if(ok.indexOf(e.charAt(i))<0){
                        return false;
                }
        }

        re = /(@.*@)|(\.\.)|(^\.)|(^@)|(@$)|(\.$)|(@\.)/;
        re_two = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$/;

        if (!e.match(re) && e.match(re_two)) {
                return (-1);
        }
}

function checkEmail(field){
        var inputStr = field.value
        if(!check_email(inputStr)){
                alert("Invalid email detected.");
                field.focus();
                field.select()
                return false;
        }
        return true;
}

function last() {

        var proceed = true

        proceed = isEmpty(document.form4.email,"Email")
        if (!proceed) return false

        proceed = checkEmail(document.form4.email)
        if (!proceed) return false

}