[英]I am trying to make a text box only be able to have 4 Digits within it
我試圖使一個文本框內最多允許4位數字,如果少於4個,則使一個警報消息框。我設法使用此代碼來做到這一點。
<tr>
<td id="ExamNumber">ExamNumber </td>
<td> <input type="text" name="ExamNumber" maxlength="4"
<font size="1">(Maximum characters: 4)</font> </td>
</tr>
if (document.ExamEntry.ExamNumber.value.length!=4) {
msg+="You must enter at least Four Numbers in the Examination Number \n";
document.ExamEntry.ExamNumber.focus();
document.getElementById('ExamNumber').style.color="red";
result = false;
}
但是,與代碼中的其他文本框相比,該文本框的尺寸縮小並且看起來很奇怪,並且它不是數字,只是文本字段中仍允許使用字母和符號。 請幫助並提前感謝您。 如果有幫助,下面是完整的代碼列表:
<head>
<title>Exam Entry Form</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.getElementById('name').style.color="red";
result = false;
}
if (document.ExamEntry.subject.value=="") {
msg+="You must enter the subject \n";
document.ExamEntry.subject.focus();
document.getElementById('subject').style.color="red";
result = false;
}
if (document.ExamEntry.ExamNumber.value=="") {
msg+="You must enter the Exam Number \n";
document.ExamEntry.ExamNumber.focus();
document.getElementById('ExamNumber').style.color="red";
result = false;
}
if (document.ExamEntry.ExamNumber.value.length!=4) {
msg+="You must enter at least Four Numbers in the Examination Number \n";
document.ExamEntry.ExamNumber.focus();
document.getElementById('ExamNumber').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="ExamNumber">ExamNumber </td>
<td> <input type="text" name="ExamNumber" maxlength="4"
<font size="1">(Maximum characters: 4)</font> </td>
</tr>
<tr>
<td><input type="submit" name="Submit" value="Submit" onclick="return validateForm();" \></td>
<td><input type="reset" name="Reset" value="Reset" /></td>
</tr>
</table>
</form>
</body>
在按鍵上使用以下代碼僅允許數字鍵。 對於文本框的寬度,請在樣式中指定寬度。
function NumericCharKeyPress()
{
if ((event.keyCode >= 48 && event.keyCode <= 57))
{
return true;
}
return false;
}
使用此代碼調整寬度:
<input type="text" maxlength="4" size="10" />
要么
<input type="text" maxlength="4" style="width:100px;" />
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