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How to validate form using JavaScript regular expression

巴扎黑Original: 2017-06-16 10:50:171077browse

This article mainly introduces the method of using JavaScript regular expressions to verify form forms. Friends who need it can refer to it

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<html> 
 <head> 
  <script type="text/javascript"> 
   function show() 
   { 
    //弹出一个提示框 
    window.alert("hh"); 
   } 
   //将show方法绑定到按钮上 
   window.onload=function() 
   { 
    //定位到按钮 
    var buttonElement=document.forms[0].mybtn; 
    //动态绑定show方法 
    buttonElement.onclick=show; 
    //show如果加()则一加载网页就弹出提示框 
   } 
   function validateForm() 
   { 
    var loginform=document.forms[1]; 
    var username=trim(loginform.username.value); 
    var password=trim(loginform.password.value); 
    var email=trim(loginform.email.value); 
//    alert("替代前长度："+username.length); 
//    username=trim(username); 
 //   alert("替代后长度："+username.length); 
    //判断用户名必填： 
    if(username.length==0) 
    { 
     alert("用户必填"); 
    } 
    else if(!/^[a-zA-Z0-9]+$/.test(username)) 
    { 
     alert("用户名必须是英文字母"); 
    } 
    else if(password.length==0) 
    { 
     alert("密码必填"); 
    } 
    else if(!/^[0-9]{6}$/.test(password)) 
    { 
     alert("密码必须为6位数字"); 
    } 
    else if(email.length==0) 
    { 
     alert("邮箱必填"); 
    } 
    else if(!/^\w+@\w+(\.\w+)+$/.test(email)) 
    { 
     alert("邮箱格式不正确"); 
    } 
    return false; 
   } 
   //自定义一个去空格的参数 
   function trim(s) 
   { 
    //s.REPLACE(正则表达式,替换的字符) 
    s=s.replace(/^\s*$/,""); 
    return s; 
   } 
  </script> 
  <style type="text/css"> 
   .myclass{ 
    position: absolute; 
    left: 400px; 
    top: 150px; 
   } 
  </style> 
 </head>  
 <body> 
  <p class="myclass"> 
  <form action="#" name="myform" method="post"> 
  <input type="button" value="单机" name="mybtn"/> 
  </form> 
  </p> 
  <!--登录页面的表单--> 
  <form action="#" name="loginform" method="post" onsubmit="return validateForm()"> 
  <table border="1" align="center"> 
   <caption>基于js的验证</caption> 
    <tr> 
     <th>用户名：</th> 
     <td><input type="text" name="username"/></td> 
    </tr> 
    <tr> 
     <th>密码：</th> 
     <td><input type="password" name="password"/></td> 
    </tr> 
    <tr> 
     <th>邮箱：</th> 
     <td><input type="text" name="email"/></td> 
    </tr> 
    <tr> 
     <td align="center" colspan="2"> 
      <input type="submit" value="提交" /> 
     </td> 
    </tr> 
  </table> 
  </form> 
 </body> 
</html>

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