Question

我想运行一个与输入数字相匹配的信用卡类型的程序，即当我从select中选择卡片类型时，如果卡片类型与输入的数字匹配，则应加载卡片的图像。我使用过切换器使用if和else case的情况。当我只运行代码时，其他部分正在运行。

我需要的是它应该显示警告信息作为有效卡和卡的图像应该显示，如果不是它应该提醒作为无效卡。这是我的代码在下面..

<script type="text/javascript">
    		function validate() 
                {
    			var a = document.getElementById("mySelect").value;
    			var b = document.getElementById("cardno").value;
    			var v = /^(?:4[0-9]{12}(?:[0-9]{3})?)$/;   
    			var e = /^(?:3[47][0-9]{13})$/;   
    			var j = /^(?:(?:2131|1800|35\d{3})\d{11})$/;
    			var element = document.getElementById("img1");
    			var element1 = document.getElementById("img2");
    			var element2 = document.getElementById("img3");
    			var card=a;
    			switch(card){
    			case "visa":
    			if (b == v) 
                {
                alert("valid");
                element.src="images/visa.jpg";
    				
    			} else {
    				
    				alert("Invalid card number,Should start with 4");
    	
    			}
                break;
    			case "ae":
    			if (b == e) {
                    alert("valid");
    				element1.src="images/ae.jpg";
    			} else {
    				alert("Invalid card number,Should start with 34 or 37 ");
    			}
    			break;
    			case "jcb":
    			if (b == j) {
                    alert("valid");
    				element2.src="images/jcb.jpg";
    			} else
    			{
    				alert("Invalid card number,Should start with 2131
or 1800");
    			}
    			break;
    			default:
    				alert("Enter valid card numbers");
    			}
    		}
    	</script>

<html>
    <head>
    <title>User Form</title>
    </head>
    <body style="background-color: palegreen">
    <div align="left" height="50%" width="40%">
<form action="user" method="post">
    			<table>
    				<tr>
    					<td><label>UserName:</label></td>
    					<td><input type="text" name="uname"
    						placeholder="Enter username" required><br> <br></td>  
    				</tr>
    				<tr>
    					<td><label>cardname:</label></td>
    					<td><select id="mySelect">
    							<option value="">SelectCard</option>
    							<option value="visa">Visa</option>
    							<option value="ae">AmericanExpress</option>
    							<option value="jcb">Jcb</option>
    					</select><br> <br></td>
    				</tr>
    				<tr>
    					<td><label>cardnumber:</label></td>
    					<td><input type="text" name="nom" id="cardno" maxlength="16"
    						pattern="/^[0-9]+$/" title="Enter Valid Card No"
    						placeholder="Enter Card number" onkeypress="validate()" required><br>
    						<br></td>
    				</tr>
    				<tr>
    					<td><label>Date Of Expiry:</label></td>
    					<td><input type="text" name="doe" placeholder="dd/MM/yyyy"
    						required><br> <br></td>
    				</tr>
    				<tr>
    					<td><label>Bill Due Date:</label></td>
    					<td><input type="text" name="dat" placeholder="dd/MM/yyyy"
    						required><br> <br></td>
    				</tr>
    				<tr>
    					<td><input type="submit" value="Add"
    						style="height: 30px; width: 100px" class="glowing-border"></td>
    				</tr>
    			</table>
    		</form>
    	</div> 
    	<img src="images/visa.jpg" id="img1" align="right" height="40"
    		width="50">
    	<img src="images/ae.jpg" id="img2" align="right" height="40" width="50">
    	<img src="images/jcb.jpg" id="img3" align="right" height="40"
    		width="50">
    </body>
    </html>

Answer 1

您正在将RegExp个对象与不起作用的字符串进行比较我猜你想用正则表达式测试字符串。这不是通过比较器（== || ===）完成的，而是通过调用regexp对象上的test方法将字符串传递给test作为参数，如下所示：

let regexpObj = /^(?:4[0-9]{12}(?:[0-9]{3})?)$/;
if (regexpObj.test("a string")) {
  // If the method returns true, its a match, else its not a match.
}

我建议您阅读有关正则表达式的MDN web docs。

jsp中的信用卡类型和号码验证

1 个答案: