如果為空，則停止表單向php檔案提交值

如果表單的至少一個變數沒有值，我想阻止我的表單提交并采取行動轉到另一個 php 檔案。

<form id="advform" class="" action="advancedsearching.php" method="GET"  onsubmit = "return validate()" autocomplete="off"   >
                <div class="modal-header align-items-center justify-content-center py-2 ">              
                    <h4 class="modal-title">Advanced Search</h4>
        
                </div>
                <div class="modal-body  ">              
                    <div class="form-group">
                        <label>Title:</label>
                        <input type="text" name="title" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                    <div class="form-group">
                        <label>Author:</label>
                        <input type="text" name="author" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                    <div class="form-group">
                        <label>ISBN:</label>
                        <input type="text"  name="isbn" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                    

                    <div class="form-group">
                        <label>Publisher:</label>
                        <input type="text"  name="publisher" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                    <div class="form-group">
                        <label>Keyword:</label>
                        <input type="text"  name="keyword" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                </div>
                <div class="modal-footer justify-content-center  ">
                    
        
                    <input type="submit" class="btn btn-dark"   value="Search" style="width:100%;border:1px solid black;">
                </div>
            </form>

嘗試添加

 <script>
function validate() {
    var x;
    x = document.getElementById("advform").value;
    if (x == "") {
        alert("Please Enter a Value");
        return false;
    };
}
</script>  

但它仍在提交

uj5u.com熱心網友回復：

    function validate() {
        var inputs = document.getElementById('advform').getElementsByTagName("input");
        for (var i = 0; i < inputs.length; i  )
        {
            if (inputs[i].type != "submit" && inputs[i].value != "") 
            {
                return true;
            }

            alert("Please Enter a Value");

            return false;
        }
    }

<form id="advform" class="" action="advancedsearching.php" method="GET"  onsubmit = "return validate()" autocomplete="off"   >
                <div class="modal-header align-items-center justify-content-center py-2 ">              
                    <h4 class="modal-title">Advanced Search</h4>
        
                </div>
                <div class="modal-body  ">              
                    <div class="form-group">
                        <label>Title:</label>
                        <input type="text" name="title" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                    <div class="form-group">
                        <label>Author:</label>
                        <input type="text" name="author" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                    <div class="form-group">
                        <label>ISBN:</label>
                        <input type="text"  name="isbn" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                    

                    <div class="form-group">
                        <label>Publisher:</label>
                        <input type="text"  name="publisher" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                    <div class="form-group">
                        <label>Keyword:</label>
                        <input type="text"  name="keyword" class="form-control"  autocomplete="off"  autocomplete="false" >
                    </div>
                </div>
                <div class="modal-footer justify-content-center  ">
                    
        
                    <input type="submit" class="btn btn-dark"   value="Search" style="width:100%;border:1px solid black;">
                </div>
            </form>

uj5u.com熱心網友回復：

嘗試使用分配給提交按鈕的事件來執行此操作：

document.getElementById("submitBtnId").addEventListener("click", function(event){
  // event.preventDefault() will stop your submit.
  event.preventDefault();
});

要繼續提交，您可以使用：

 event.currentTarget.submit();

uj5u.com熱心網友回復：

它不起作用，因為您的表單中有 id，它應該在您要驗證的輸入中。

另一種方式是在輸入中使用所需的屬性

<input type="text"  name="publisher" class="form-control"  autocomplete="off"  autocomplete="false" required>

https://www.w3schools.com/tags/att_input_required.asp

標籤：javascript html 形式

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