我有一个 javascript 来检查我的表单是否有效并在某个字段后停止检查

如何解决我有一个 javascript 来检查我的表单是否有效并在某个字段后停止检查

所以我在 html 的表格中创建了一个表单，javascript 代码检查直到 (creditcard.value.length) 之后代码不检查任何内容

<script language="javascript" type="text/javascript">
     function ispsd(form) {
       var passed = false;

       if (form.Fullname.value.length < 4) {
         alert("Enter a valid Full Name");
       } else if (form.Email.value.indexOf("@") == -1) {
         alert("Enter a valid E-mail adress.")
       } else if (form.Email.value.indexOf(".") == -1) {
         alert("Enter a valid E-mail adress.")
       } else if (form.Cardholder.value.length < 3) {
        alert("Card Holder name is not Valid.")
       } else if (form.Creditcard.value.length != 16) {
         alert("Credit card number is not valid.")
       } else if (isNan(form.Creditcard.value)) {
         alert("Credit card number cannot contain letters.")
       } else if (isNan(form.Zip.value)) {
         alert("Enter a valid Postal Code.")
       } else if ((form.Expyear.value) * 1 < 2021) {
         alert("Credit Card has Expired.")
       } else if (isNan(form.Expyear.value)) {
         alert("Enter a valid Year.")
       } else if (form.cvv.value.length != 3) {
         alert("Enter a valid CVV.")
       } else if (isNan(form.cvv.value)) {
         alert("CVV cannot contain letters.")
       } else {
         passed = true;
       }
       return passed;
     }
</script>

问题是当我将 (form.Expyear.value) * 1

不知道是什么问题 如果有人可以帮助我将不胜感激

解决方法

• 尝试删除* 1，不确定那里的用途
• isNaN，而不是 isNan

我也会以不同的方式处理它，您需要的是如果它们通过则返回true，而不是识别错误，例如，下面的演示。例如，如果您在检查 x !== 16

后有超过 16 个数字，它将通过您的测试

function validate() {
  var x,text;

    // Get the value of the input field with id="numb"
    x = document.getElementById("cc").value;

    // If x is Not a Number or less than one or greater than 10
    if (!isNaN(x) && x.length > 3 && x.length <= 16) {
      text = "Input OK";
    } else {
      text = "Input not valid";
    }
    document.getElementById("error").innerHTML = text;
}

<p>Please write only numbers,from 4 to 16 maximum characters</p>
<input type="number" id="cc"/><br>
<span id="error"></span><br>
<input type="submit" onclick="validate()" />

最后但并非最不重要的是，这太冗长且难以维护，我强烈建议使用像 https://www.npmjs.com/package/validator 这样的库来处理验证，甚至 jQuery 也有 .validate() 对初学者有用的功能。>

,

你总是可以使用console.log()来检查变量有什么

function validate(form) {
    if (form.Fullname.value.length < 4) {
        alert('Enter a valid Full Name');
        document.form.Fullname.focus();
        return false;
    }

    if (form.Email.value.indexOf('@') == -1 || form.Email.value.indexOf('.') == -1) {
        alert('Enter a valid E-mail adress.');
        document.form.Email.focus();
        return false;
    }

    if (form.Cardholder.value.length < 3) {
        alert('Card Holder name is not Valid.');
        document.form.Cardholder.focus();
        return false;
    }

    console.log(form.Creditcard.value);

    if (isNaN(form.Creditcard.value)) {
        alert('Credit card number cannot contain letters.');
        document.form.Creditcard.focus();
        return false;
    }

    if (form.Creditcard.value.length < 16) {
        alert('Credit card number is not valid.');
        document.form.Creditcard.focus();
        return false;
    }

    if (isNaN(form.Zip.value)) {
        alert('Enter a valid Full Name');
        document.form.Zip.focus();
        return false;
    }

    if (isNaN(form.Expyear.value)) {
        alert('Enter a valid Year.');
        document.form.Expyear.focus();
        return false;
    }

    if (Number(form.Expyear.value) < 2021) {
        alert('Enter a valid Year.');
        document.form.Expyear.focus();
        return false;
    }

    if (isNaN(form.cvv.value)) {
        alert('CVV cannot contain letters.');
        document.form.cvv.focus();
        return false;
    }

    if (form.cvv.value.length != 3) {
        alert('Enter a valid Year.');
        document.form.cvv.focus();
        return false;
    }

    return true;
}