Posted: Tue, Mar 8 05:50 PM (PST)
An easy way to validate credit card number with one function in JavaScript
function isValidCardNumber(cardNumber) {
var nCheck = 0;
var nDigit = 0;
var bEven = false;
for (n = cardNumber.length - 1; n >= 0; n--) {
var cDigit = cardNumber.charAt(n);
if (isDigit(cDigit)) {
var nDigit = parseInt(cDigit, 10);
if (bEven) {
if ((nDigit *= 2) > 9)
nDigit -= 9;
}
nCheck += nDigit;
bEven = ! bEven;
}
else if (cDigit != ' ' && cDigit != '.' && cDigit != '-') {
return false;
}
}
return (nCheck % 10) == 0;
}
function isDigit(c) {
var strAllowed = "1234567890";
return (strAllowed.indexOf(c) != -1);
}
function isCardTypeCorrect(cardNumber, type) {
var nLen = 0;
for (n = 0; n < cardNumber.length; n++) {
if (isDigit(cardNumber.substring(n, n + 1)))
++nLen;
}
if (type == 'Visa')
return ((cardNumber.substring(0, 1) == '4') && (nLen == 13 || nLen == 16));
else if (type == 'Amex')
return ((cardNumber.substring(0, 2) == '34' || cardNumber.substring(0, 2) == '37') && (nLen == 15));
else if (type == 'Master Card')
return ((cardNumber.substring(0, 2) == '51' || cardNumber.substring(0, 2) == '52'
|| cardNumber.substring(0, 2) == '53' || cardNumber.substring(0, 2) == '54'
|| cardNumber.substring(0, 2) == '55') && (nLen == 16));
else
return false;
}
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Posted: Tue, Mar 8 05:32 PM (PST)
Here is the code to validate email address in JavaScript using regular expression.
function validate(form_id,email) {
var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
var address = document.forms[form_id].elements[email].value;
if(reg.test(address) == false) {
alert('Invalid Email Address');
return false;
}
}
In the forms 'onsubmit' code call javascript:return validate('form_id','email_field_id')
<form id="form_id" method="post" action="action.php" onsubmit="javascript:return validate('form_id','email');">
<input type="text" id="email" name="email" />
<input type="submit" value="Submit" />
</form>
You should not rely purely on client side validation on your website / web application, if the user has javascript disabled this will not work. Always validate on the server.
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