Javascript 验证文本框,以便必须输入值
嗨,我试图让这段代码来验证文本框,所以它们必须包含一个值;如果他们没有,我希望出现一条消息,说明字段不能为空。以下是我编写的代码:Javascript 验证文本框,以便必须输入值,javascript,validation,Javascript,Validation,嗨,我试图让这段代码来验证文本框,所以它们必须包含一个值;如果他们没有,我希望出现一条消息,说明字段不能为空。以下是我编写的代码: <head> <title>Exam entry</title> <script language="javascript" type="text/javascript"> function validateForm() { var result = true; var msg="";
<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>
报考
函数validateForm(){
var结果=真;
var msg=“”;
if(document.ExamEntry.name.value==“”){
msg+=“您必须输入您的姓名\n”;
document.ExamEntry.name.focus();
document.gotElementById('name').style.color=“red”;
结果=假;
}
if(document.ExamEntry.subject.value==“”){
msg+=“您必须输入主题\n”;
document.ExamEntry.subject.focus();
document.gotElementById('subject').style.color=“red”;
结果=假;
}
if(document.ExamEntry.examno.value==“”){
msg+=“您必须输入考试编号\n”;
document.ExamEntry.examno.focus();
document.gotElementById('examno').style.color=“red”;
结果=假;
如果(msg==“”){
返回结果;
}
{
警报(msg)
返回结果;
}
}
报考表
名称
主题
考试号码
任何帮助都很好,谢谢属性值不能直接用于元素,您应该始终使用:
element.getAttribute('value')
这将获得value属性
希望这有帮助
值
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
}
}
函数设置错误(fld、id、msg){
如果(fld.value==“”){
document.getElementById(id).className=“error”;
返回味精;
}
document.getElementById(id).className=“正常”;
返回“”;
}
window.onload=function(){
document.getElementById(“ExamEntry”).onsubmit=function(){
var msg,msgs=[],focusField=“”;
msg=setError(this.fullName,“fullnamelab”,“您必须输入您的姓名”);
if(msg){msgs.push(msg);focusField=this.fullName;}
msg=setError(this.subject,“subjectLabel”,“您必须输入主题”);
if(msg){msgs.push(msg);focusField=focusField | | this.subject;}
var examno=this.examno;
msg=setError(examno,“examnoLabel”,“您必须输入检查编号”);
if(msg){msgs.push(msg);focusField=focusField | | examno;}
否则{
如果(isNaN(examno.value)| | examno.value.length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
将给您带来问题,因为ExamEntry
表单已经有一个名为name
的属性。您应该重命名字段,或者使用:
document.ExamEntry.elements['name'].value
你错过了一个}在第三个if的末尾。还有,有很多代码重复,试着在函数中进行抽象。嗯?你是如何得出这个结论的?非常感谢,因为你可以告诉我我是一个新手!我现在可以看到我错在哪里了,非常感谢你的帮助!如果我要扩展考试编号字段以验证考试编号至少为4 n长度是多少?我该怎么做?