參照圖靈叢書上面的檢查日期格式例子，其中html代碼如下：<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>無標題文檔</title>
<script type="text/javascript" src="checkdate.js"></script>
<style type="text/css">
.error{
color:#c00;
font-weight:bold;
}
</style>
</head>
<body>
<h1>Event Search</h1>
<form action="Js_2.html" method="post" οnsubmit="return checkDate();">
<p>
<label for="date">Date in format DD/MM/YY:</label><br />
<input type="text" id="date" name="date" />
<input type="submit" value="Check" />
<!-- 注意此處span標籤中間有一個空格-->
<br />(example 24/04/1975)<span class="error"> </span>
</p>
</form>
</body>
</html>
checkdate.js部分代碼如下：
// JavaScript Document
function checkDate(){
if(!document.getElementById || !document.createTextNode){return;}
var dateField = document.getElementById('date');
if(!dateField){return;}
var errorContainer = dateField.parentNode.getElementsByTagName('span')[0];
if(!errorContainer){return;}
var checkPattern = new RegExp("\\d{2}/\\d{2}/\\d{4}");
var errorMessage = '';
errorContainer.firstChild.nodeValue = ' ';
var dateValue = dateField.value;
if(dateValue == ''){
errorMessage = 'Please provide a date.';
}else if(!checkPattern.test(dateValue))
{
errorMessage = 'Please provide the date in the defined format.';
}
if(errorMessage!=' ')
{
errorContainer.firstChild.nodeValue = errorMessage;
dateField.focus();
return false;
}else{
return true;
}
}