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Luhn algorithm - JavaScript implementation
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| function CreditCardValidator() { | |
| } | |
| CreditCardValidator.prototype = { | |
| isValid: function (identifier) { | |
| var num, | |
| sum = 0, | |
| alt; | |
| var myRegxp = /^([0-9]){13,19}$/; | |
| if (myRegxp.test(identifier.length)) { | |
| return false; | |
| } | |
| var i = identifier.length - 1; | |
| while (i >= 0) { | |
| num = parseInt(identifier.charAt(i), 10); | |
| if (isNaN(num)) { | |
| return false; | |
| } | |
| if (alt) { | |
| document.write(num); | |
| num = num * 2; | |
| if (num > 9) { | |
| num = num - 9; | |
| } | |
| } | |
| alt = !alt; | |
| sum = sum + num; | |
| i--; | |
| } | |
| return (sum % 10 == 0); | |
| } | |
| } |
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Learn more about bidirectional Unicode characters
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset=utf-8 /> | |
| <title>JS Bin</title> | |
| <script type="text/javascript" src="CreditCardValidator.js"></script> | |
| </head> | |
| <body> | |
| <script TYPE="text/javascript"> | |
| var valid = new CreditCardValidator(); | |
| alert(valid.isValid("0123765443210190")); | |
| </script> | |
| </body> | |
| </html> |
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