Question

您好我正在尝试使用此代码验证文本框，因此它们必须包含值;如果他们不要我想要一条消息，说明这些字段不能为空。这是我写的代码：

<head>
<title>Exam entry</title>
<script language="javascript" type="text/javascript">

function validateForm() {
    var result = true;
    var msg="";

        if (document.ExamEntry.name.value=="") {
        msg+="You must enter your name \n";
        document.ExamEntry.name.focus();
        document.gotElementById('name').style.color="red";
        result = false;
    }

        if (document.ExamEntry.subject.value=="") {
        msg+="You must enter the subject \n";
        document.ExamEntry.subject.focus();
        document.gotElementById('subject').style.color="red";
        result = false;
    }

        if (document.ExamEntry.examno.value=="") {
        msg+="You must enter an examination number \n";
        document.ExamEntry.examno.focus();
        document.gotElementById('examno').style.color="red";
        result = false;

    if(msg==""){
    return result;
    }

    {
    alert(msg)
    return result;
    }
}

</script>
</head>

<body>
<h1>Exam Entry Form</h1>
<form name="ExamEntry" method="post" action="success.html">
<table width="50%" border="0">
    <tr>
        <td id="name">Name</td>
        <td><input type="text" name="name" /></td>
    </tr>
    <tr>
        <td id="subject">Subject</td>
        <td><input type="text" name="subject" /></td>
    </tr>
    <tr>
        <td id="examno">Examination Number</td>
        <td><input type="integer" name="examno" /></td>
    </tr>

<tr>
    <td><input type="submit" name="Submit" value="Submit" onclick="return validationFrom();" /></td>
    <td><input type="reset" name="Reset" value="Reset" /></td>
</tr>

</table>
</form>
</body>

任何帮助都会非常感谢

Answer 1

getElementById而不是gotelementById
使用fullName而不是保留字名称
不要使用与表单名称相同的ID - IE会被混淆
不要使用提交按钮的onclick。而是使用表单onsubmit
您可能不会被允许POST到HTML文件
HTML5支持type =＆＃34; number＆＃34;不是＆＃34;整数＆＃34;
将属性value添加到每个字段

以下是我的建议 - DEMO

我更改了标签ID并将名称更改为fullName

function setError(fld,id,msg) {

   if (fld.value=="") {
     document.getElementById(id).className="error";
     return msg;
   }
   document.getElementById(id).className="normal";
   return "";

}
window.onload=function() {
  document.getElementById("ExamEntry").onsubmit=function() {

    var msg,msgs=[],focusField="";
    msg=setError(this.fullName,"fullNameLabel","You must enter your name");
    if (msg) { msgs.push(msg); focusField = this.fullName;}
    msg=setError(this.subject,"subjectLabel","You must enter the subject");
    if (msg) {  msgs.push(msg); focusField = focusField || this.subject;}

    var examno = this.examno;
    msg = setError(examno,"examnoLabel","You must enter an examination number");
    if (msg) { msgs.push(msg); focusField = focusField || examno;}
    else {
      if (isNaN( examno.value) ||  examno.value.length<4) {
        msgs.push("You must enter a valid examination number");
        document.getElementById("examnoLabel").className="error"
        focusField = focusField || this.examno;
      }
    }
    if(focusField) {
      alert(msgs.join("\n"));
      focusField.focus();
      return false;
    }
    return true; // allow submission
  }
}

Answer 2

如果使用保留字命名输入元素，例如name，则会遇到问题。代码：

document.ExamEntry.name.value

会导致您遇到问题，因为ExamEntry表单已经有一个名为name的属性。您应该重命名字段，或使用：

document.ExamEntry.elements['name'].value

Answer 3

属性值不能直接用于元素，您应该始终使用：

element.getAttribute('value')

这将为您提供值属性。

希望这有帮助。

验证文本框，以便输入值

3 个答案: