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Thread: validation fails and page submits on error :(

  1. #1
    Join Date
    Mar 2008
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    Default validation fails and page submits on error :(

    Hey,

    I am using a creditcard validation script within a php page, however the script will pop up to tell you there is an error, but still submits the page...

    any ideas?

    this is in the head, before a style code
    Code:
    <script type="text/javascript" src="creditcard.js"></script>
    <script type="text/javascript">
    <!--
    function testCreditCard () {
      if (checkCreditCard (document.getElementById('payee_cardNum').value,document.getElementById('payee_cardType').value)) {
        alert ("Credit card has a valid format")
      } 
      else {alert (ccErrors[ccErrorNo])};
    }
    //-->
    </script>
    my submit button
    Code:
    <input type="submit" name="pay" id="pay" value="Make Payment" onclick="testCreditCard();" />
    my creditcard.js
    Code:
    /*============================================================================*/
    
    /*
    
    This routine checks the credit card number. The following checks are made:
    
    1. A number has been provided
    2. The number is a right length for the card
    3. The number has an appropriate prefix for the card
    4. The number has a valid modulus 10 number check digit if required
    
    If the validation fails an error is reported.
    
    The structure of credit card formats was gleaned from a variety of sources on 
    the web, although the best is probably on Wikepedia ("Credit card number"):
    
      http://en.wikipedia.org/wiki/Credit_card_number
    
    Parameters:
                cardnumber           number on the card
                cardname             name of card as defined in the card list below
    
    Author:     John Gardner
    Date:       1st November 2003
    Updated:    26th Feb. 2005      Additional cards added by request
    Updated:    27th Nov. 2006      Additional cards added from Wikipedia
    Updated:    18th Jan. 2008      Additional cards added from Wikipedia
    
    */
    
    /*
       If a credit card number is invalid, an error reason is loaded into the 
       global ccErrorNo variable. This can be be used to index into the global error  
       string array to report the reason to the user if required:
       
       e.g. if (!checkCreditCard (number, name) alert (ccErrors(ccErrorNo);
    */
    
    var ccErrorNo = 0;
    var ccErrors = new Array ()
    
    ccErrors [0] = "Unknown card type";
    ccErrors [1] = "No card number provided";
    ccErrors [2] = "Credit card number is in invalid format";
    ccErrors [3] = "Credit card number is invalid";
    ccErrors [4] = "Credit card number has an inappropriate number of digits";
    
    function checkCreditCard (cardnumber, cardname) {
         
      // Array to hold the permitted card characteristics
      var cards = new Array();
    
      // Define the cards we support. You may add addtional card types.
      
      //  Name:      As in the selection box of the form - must be same as user's
      //  Length:    List of possible valid lengths of the card number for the card
      //  prefixes:  List of possible prefixes for the card
      //  checkdigit Boolean to say whether there is a check digit
      
      cards [0] = {name: "Visa", 
                   length: "13,16", 
                   prefixes: "4",
                   checkdigit: true};
      cards [1] = {name: "MasterCard", 
                   length: "16", 
                   prefixes: "51,52,53,54,55",
                   checkdigit: true};
      cards [2] = {name: "Solo", 
                   length: "16,18,19", 
                   prefixes: "6334, 6767",
                   checkdigit: true};
      cards [3] = {name: "Switch", 
                   length: "16,18,19", 
                   prefixes: "4903,4905,4911,4936,564182,633110,6333,6759",
                   checkdigit: true};
      cards [4] = {name: "Maestro", 
                   length: "16,18", 
                   prefixes: "5020,6",
                   checkdigit: true};
      cards [5] = {name: "VisaElectron", 
                   length: "16", 
                   prefixes: "417500,4917,4913",
                   checkdigit: true};
                   
      // Establish card type
      var cardType = -1;
      for (var i=0; i<cards.length; i++) {
    
        // See if it is this card (ignoring the case of the string)
        if (cardname.toLowerCase () == cards[i].name.toLowerCase()) {
          cardType = i;
          break;
        }
      }
      
      // If card type not found, report an error
      if (cardType == -1) {
         ccErrorNo = 0;
         return false; 
      }
       
      // Ensure that the user has provided a credit card number
      if (cardnumber.length == 0)  {
         ccErrorNo = 1;
         return false; 
      }
        
      // Now remove any spaces from the credit card number
      cardnumber = cardnumber.replace (/\s/g, "");
      
      // Check that the number is numeric
      var cardNo = cardnumber
      var cardexp = /^[0-9]{13,19}$/;
      if (!cardexp.exec(cardNo))  {
         ccErrorNo = 2;
         return false; 
      }
           
      // Now check the modulus 10 check digit - if required
      if (cards[cardType].checkdigit) {
        var checksum = 0;                                  // running checksum total
        var mychar = "";                                   // next char to process
        var j = 1;                                         // takes value of 1 or 2
      
        // Process each digit one by one starting at the right
        var calc;
        for (i = cardNo.length - 1; i >= 0; i--) {
        
          // Extract the next digit and multiply by 1 or 2 on alternative digits.
          calc = Number(cardNo.charAt(i)) * j;
        
          // If the result is in two digits add 1 to the checksum total
          if (calc > 9) {
            checksum = checksum + 1;
            calc = calc - 10;
          }
        
          // Add the units element to the checksum total
          checksum = checksum + calc;
        
          // Switch the value of j
          if (j ==1) {j = 2} else {j = 1};
        } 
      
        // All done - if checksum is divisible by 10, it is a valid modulus 10.
        // If not, report an error.
        if (checksum % 10 != 0)  {
         ccErrorNo = 3;
         return false; 
        }
      }  
    
      // The following are the card-specific checks we undertake.
      var LengthValid = false;
      var PrefixValid = false; 
      var undefined; 
    
      // We use these for holding the valid lengths and prefixes of a card type
      var prefix = new Array ();
      var lengths = new Array ();
        
      // Load an array with the valid prefixes for this card
      prefix = cards[cardType].prefixes.split(",");
          
      // Now see if any of them match what we have in the card number
      for (i=0; i<prefix.length; i++) {
        var exp = new RegExp ("^" + prefix[i]);
        if (exp.test (cardNo)) PrefixValid = true;
      }
          
      // If it isn't a valid prefix there's no point at looking at the length
      if (!PrefixValid) {
         ccErrorNo = 3;
         return false; 
      }
        
      // See if the length is valid for this card
      lengths = cards[cardType].length.split(",");
      for (j=0; j<lengths.length; j++) {
        if (cardNo.length == lengths[j]) LengthValid = true;
      }
      
      // See if all is OK by seeing if the length was valid. We only check the 
      // length if all else was hunky dory.
      if (!LengthValid) {
         ccErrorNo = 4;
         return false; 
      };   
      
      // The credit card is in the required format.
      return true;
    }
    
    /*============================================================================*/

  2. #2
    Join Date
    May 2009
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    Default return

    You need to return the function call

    like this: onclick="return testCreditCard();"

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