使用javascript

Question

我一直试图完成这项工作，但没有成功。我使用正则表达式来验证用户根据通过单选按钮选择的信用卡类型输入的信用卡号。     但是我想知道所有 if 语句的警报。看起来所有 if else 语句都经过测试。

There is the HTML code fragment: 

<code>
<p><b>Payment Information:</b></p>
         <fieldset>
            <input type="radio" name="payment" value="Visa" id="visa" />Visa &nbsp;
            <input type="radio" name="payment" value="Master Card" />Master Card &nbsp;
            <input type="radio" name="payment" value="American Express" />American Express &nbsp;
            <input type="radio" name="payment" value="Discover" />Discover <br /><br />
            <label>Card Number:</label>
            <input type="text" name="cardNumber" id="cardNum" size="30" value="" onblur="ValidateCreditCardNumber()" />
</code>



And there is my javascript function :

<code>

function ValidateCreditCardNumber(){

    var ccNum = document.getElementById("cardNum").value;



    var visaRegEx = /^(?:4[0-9]{12}(?:[0-9]{3})?)$/;
    var mastercardRegEx = /^(?:5[1-5][0-9]{14})$/;
    var amexpRegEx = /^(?:3[47][0-9]{13})$/;
    var discovRegEx = /^(?:6(?:011|5[0-9][0-9])[0-9]{12})$/; 


    if (visaRegEx.test(ccNum) === false ){ // Visa validation
       alert("Please provide a valid Visa number!");   
        }  
      else  
        {  
         alert("Thank You!");  
        }  

    if (mastercardRegEx.test(ccNum) === false){ // MasterCard validation
        alert("Please provide a valid MasterCard number!");  
        }  
      else  
        {  
        alert("Thank You!");  
        } 

    if(amexpRegEx.test(ccNum) === false){ // Amex  validation
        alert("Not a valid America Express number!");  
        }  
      else  
        {   
        alert("Thank You!");  
        } 

    if (discovRegEx.test(ccNum) === false){ // Discover validation
        alert("Please provide a valid Discover number!"); 
        }  
      else  
        {  
        alert("Thank You!");  
        } 


    }
</code>


Any kind of help or advice would be really appreciated.

Answer 1

在您的情况下，您有4个不同的if块，当前一次失败时会触及每个块。

将if替换为if else，这样只会验证单个用例。 此外，您无需让用户知道他想要输入的卡类型。输入有效数字只需一条消息即可。

function ValidateCreditCardNumber() {

  var ccNum = document.getElementById("cardNum").value;
  var visaRegEx = /^(?:4[0-9]{12}(?:[0-9]{3})?)$/;
  var mastercardRegEx = /^(?:5[1-5][0-9]{14})$/;
  var amexpRegEx = /^(?:3[47][0-9]{13})$/;
  var discovRegEx = /^(?:6(?:011|5[0-9][0-9])[0-9]{12})$/;
  var isValid = false;

  if (visaRegEx.test(ccNum)) {
    isValid = true;
  } else if(mastercardRegEx.test(ccNum)) {
    isValid = true;
  } else if(amexpRegEx.test(ccNum)) {
    isValid = true;
  } else if(discovRegEx.test(ccNum)) {
    isValid = true;
  }

  if(isValid) {
     alert("Thank You!");
  } else {
     alert("Please provide a valid Visa number!");
  }
}

Answer 2

将您的逻辑更改为：

<script type="text/javascript">

// Store the regexes as globals so they're cached and not re-parsed on every call:
var visaPattern = /^(?:4[0-9]{12}(?:[0-9]{3})?)$/;
var mastPattern = /^(?:5[1-5][0-9]{14})$/;
var amexPattern = /^(?:3[47][0-9]{13})$/;
var discPattern = /^(?:6(?:011|5[0-9][0-9])[0-9]{12})$/; 

function validateCreditCardNumber() {

    var ccNum  = document.getElementById("cardNum").value;

    var isVisa = visaPattern.test( ccNum ) === true;
    var isMast = mastPattern.test( ccNum ) === true;
    var isAmex = amexPattern.test( ccNum ) === true;
    var isDisc = discPattern.test( ccNum ) === true;

    if( isVisa || isMast || isAmex || isDisc ) {
        // at least one regex matches, so the card number is valid.

        if( isVisa ) {
            // Visa-specific logic goes here
        }
        else if( isMast ) {
             // Mastercard-specific logic goes here
        }
        else if( isAmex ) {
            // AMEX-specific logic goes here
        }
        else if( isDisc ) {
            // Discover-specific logic goes here
        }
    }
    else {
        alert("Please enter a valid card number.");
    }
}

</script>

Answer 3

这应该做的工作

var cc = /^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|(222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}|6(?:011|5[0-9][0-9])[0-9]{12}|3[47][0-9]{13}|3(?:0[0-5]|[68][0-9])[0-9]{11}|(?:2131|1800|35\d{3})\d{11}|62[0-9]{14})$/

cc.test(card_number)

来源：vee-validate repo