Question

我正在尝试运行一个脚本，看看我是否可以验证文本框中的前4个字符。文本框告诉我字符不在那里但是当我正确地放入前4个数字时它仍然给我同样的错误。此外，文本框最少包含15个字符，最多16个字符。

这是脚本：

var check_card_no = function (event){
check_digits = card_no.substring(0, 4);
if(check_digits=="9999"){
return true;
}
else{
    alert("please enter valid Credit Card Number");
    patron_card_no.value="";
    patron_card_no.focus();
    return false;
}
}

这样每个人都能看到完整的代码就是剧本的全部内容：

<script type="text/javascript">
// Caspio form elements  kkw
var Ticket_PriceField = document.getElementById('InsertRecordTicket_Price');
var Number_of_TicketsField = document.getElementById('InsertRecordNumber_of_Tickets');
var totalField = document.querySelectorAll('span[class^="cbParamVirtual4"]')[0];
var patron_card_no = document.getElementById('InsertRecordPatron_Credit_Card_Number');
var card_no=patron_card_no.value;
var card_date=document.getElementById('InsertRecordPatron_Credit_Card_Exp');
var caspioForm = document.getElementById('caspioform');
// Event handler
var calculateTotal = function (event)
{
// TODO: Do something on value change -->
totalField.innerHTML = Ticket_PriceField.value * Number_of_TicketsField.value;
}
// Run total calculation on input
Number_of_TicketsField.addEventListener('input', calculateTotal);


// credit card no check
var check_card_no = function (event){

check_digits = card_no.substring(0, 4);
if(check_digits=="9999" ){
return true;
}
else{
    alert("please enter valid Credit Card Number");
    patron_card_no.value="";
    patron_card_no.focus();
    return false;
}
}
patron_card_no.addEventListener('change', check_card_no);


function check_credit_card_date(){
var credit_card_date=card_date.value;
var card_month=credit_card_date.substring(0, 2);
var card_year=credit_card_date.substring(2, 4);
if(credit_card_date.length==4 && (card_month > 0 && card_month < 13) && (card_year > 16 && card_month < 31) ){
return true;
}
else
{
    alert("please enter valid Credit Card Exp. Date ");
    card_date.value="";
    card_date.focus();
    return false;
}
}
card_date.addEventListener('change', check_credit_card_date);
</script>

Answer 1

除非你有某种框架在视图和你的javascript之间提供绑定，否则当你更改它时，你必须再次阅读<input>。

Answer 2

假设您将String输入传递给您的函数。

＆＃13;

var check_card_no = function (card_no){
check_digits = card_no.substring(0, 4);
if(check_digits=="9999"){
	return true;
}
else{
    //alert("please enter valid Credit Card Number");
    //patron_card_no.value="";
    //patron_card_no.focus();
    return false;
}
}


console.log('Valid Card test= '+check_card_no('99992222'));
console.log('Invalid Card test= '+check_card_no('2288888'));

＆＃13;

Javascript测试，看看前4个字符是否正确

2 个答案: