4-15编程练习

来源：4-15 编程练习

soso_crazy

2019-02-12 11:21:15

<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <title></title>
    <style>
        .oneline {
            line-height: 1.5;
            margin: 10px auto;
        }
        
        .oneline label {
            width: 100px;
            text-indent: 15px;
            font-size: 14px;
            font-family: "Microsoft Yahei";
            display: inline-block;
        }
        
        .oneline .sinput {
            width: 60%;
            height: 30px;
            border-radius: 6px;
            border: 1px solid #e2e2e2;
        }
        
        .oneline input[type="submit"] {
            margin-left: 20px;
            width: 80px;
            height: 30px;
            border: 0;
            background-color: #5899d0;
            color: #fff;
            font-size: 14px;
            border-radius: 6px;
        }
        
        .error-messages {
            color: red;
        }
    </style>
</head>
<body>
    <form id="forms">
        <div class="oneline">
            <label for="name">用户名:</label>
            <input id="name" class="sinput" name="name" type="text" required>
        </div>
        <div class="oneline">
            <label for="email">Email:</label>
            <input id="email" class="sinput" name="email" type="email" required>
        </div>
        <div class="oneline">
            <input type="submit" id="submits" value="提交">
        </div>
    </form>
    <script>
    function replaceValidationUI(form) {
        form.addEventListener("invalid", function(event) {
            event.preventDefault();
        }, true);
        form.addEventListener("submit", function(event) {
            if (!this.checkValidity()) {
                event.preventDefault();
            }
        });
        //此处写代码
        
     var submitButton=document.getElementById("submits");
     
      submitButton.addEventListener('click',function(event){
        var  invalidFields=form.querySelectorAll(':invalid'),
            errorMessage=form.querySelectorAll('.error-messages'),
            parent;
            
        for(var i=0;i<errorMessage.length;i++){
            errorMessage[i].parentNode.removeChild(errorMessage[i]);
           }
           
           
        for(var i=0;i<invalidFields.length;i++){
          parent=invalidFields[i].parentNode.parentNode;
          parent.insertAdjacentHTML('afterbegin',"<div class='error-messages'>"+inValidityField[i].validationMessage+ "</div>");
        }
        
         if (invalidFields.length > 0) {
            invalidFields[0].focus();
        }
    })
    var forms = document.getElementById("forms");
    replaceValidationUI(forms);
    
    
    </script>
</body>

</html>

为什么不能实现，问题出在哪？
麻烦老师讲讲思路，不太明白每一段JS代码的意思
for(var i=0;i<invalidFields.length;i++){
parent=invalidFields[i].parentNode.parentNode;
parent.insertAdjacentHTML('afterbegin',"<div class='error-messages'>"+inValidityField[i].validationMessage+ "</div>");
}为什么要找父节点的父节点？有什么意义？详细讲解这一段

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