Question

我有一个文本框，我用JS查看文本框是否为空。如果为空，则会在文本框下方显示错误消息。

现在，当我返回并在空文本框中输入文本时，错误消息仍然存在。如何重新检查用户是否输入了任何文本，然后自动删除错误链接。

＆＃13;

<label for="last_name_field">Last Name <abbr title="Required">*</abbr></label>
	        		<input type="text" id="last_name_field" name="lastname" placeholder="Last Name" onblur="validateLN()">

＆＃13;

 function validateLN() {
   if (document.form.lastname.value == "") { //create an error message
     var msg = " Last Name cannot be blank";
     //call the display error function
     displayError(document.form.lastname, msg);
   }



 }


 function displayError(element, msg) {
   if (element.nextSibling.tagName == "SPAN" && element.nextSibling.textContent.trim == msg.trim) {
     return;
   } else {

     var msgElement = document.createElement("span");
     msgElement.textContent = msg;
     msgElement.style.color = "red";
     element.parentNode.insertBefore(msgElement, element.nextSibling);
     element.style.border = "solid 1px red";
   }
 }

＆＃13;

Answer 1

从文本框的onchange事件中删除错误。

function validateLN() {
    if (document.form.lastname.value == "") { //create an error message
        var msg = " Last Name cannot be blank";
        //call the display error function
        displayError(document.form.lastname, msg);
    }
}

document.form.lastname.onchange = function() {
    document.getElementById('errorMsg').remove();
}

function displayError(element, msg) {
    if (element.nextSibling.tagName == "SPAN" && element.nextSibling.textContent.trim == msg.trim) {
        return;
    } else {
        var msgElement = document.createElement("span");
        msgElement.id = 'errorMsg';
        msgElement.textContent = msg;
        msgElement.style.color = "red";
        element.parentNode.insertBefore(msgElement, element.nextSibling);
        element.style.border = "solid 1px red";
    }
}

或者只是将其保留在那里并切换其display值：

var msgElement = document.createElement("span");
msgElement.id = 'errorMsg';
msgElement.textContent = msg;
msgElement.style.color = "red";
msgElement.style.display = 'none';
element.parentNode.insertBefore(msgElement, element.nextSibling);
element.style.border = "solid 1px red";

function validateLN() {
    if (document.form.lastname.value == "") { //create an error message
        var msg = " Last Name cannot be blank";
        //call the display error function
        document.getElementById('errorMsg').style.display = 'inline';
    }
}

document.form.lastname.onchange = function() {
    document.getElementById('errorMsg').style.display = 'none';
}

javascript验证：通过文本框删除错误消息

1 个答案: