.HTML代码如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <Meta http-equiv="content-type" content="text/html;charset=gbk"/> <title>RegExp用法</title> <script type="text/javascript"> function chkEmail(){ var email = document.getElementById('email').value; var obj = document.getElementById('showMess'); //www@163.com var pattern = /^[a-zA-Z]\w+[@]\w+[.][\w.]+$/;//<pre name="code" class="html">^[a-zA-Z]<span style="font-family: Arial,Helvetica,sans-serif;">表示以字母开头</span>if(pattern.test(email)){obj.innerText = "正确";obj.style.color = 'green';}else{obj.innerText = "错误";obj.style.color = 'red';}}</script></head><body><label>电子邮件:</label><input type="text" id="email" onblur="chkEmail()"/><span id="showMess"></span></body></html> 结果如下：
