JS判断不能为空实例代码。分享在此。

 代码如下:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <meta http-equiv="Content-Type" content="text/html"; charset="utf-8">
        <title>短信系统 - www.jbxue.com </title>
<script language="javascript">        
        function formcheck(){
            if(document.form.zhanghao.value==""){
                alert("号码不能为空！");
                this.form1.zhanghao.focus();
                return false;
            }else if(document.form.email.value==""){
                alert("内容不能为空！")
                this.form1.eamil.focus();
                return false;
            }else form1.submit();  
}
        </script>
    </head>    <body>
        <form name="form" method="post" action="sendmail.php" class="formg">
            <table>
                <h2> 
                    <tr>
                        <th colspan="8" class="CTitle">发送短信</th>
                    </tr>
                </h2>                 <body>
                        <tr bgcolor="#eeeeee">
                            <td align="center">号   码:</td>
                            <td><textarea name="content" cols="80" rows="15" id="zhanghao" class="formh"></textarea></td>
                        </tr>
                        <tr bgcolor="#eeeeee">
                            <td align="center">内   容:</td>
                            <td><textarea name="content" cols="80" rows="15" id="email" class="formh"></textarea></td>
                        </tr>                        <tr bgcolor="#eeeeee" align="center"> 
                <td height="25" colspan="2"> 
                    <input type="button" name="Submit" value="发 送" class="button" onClick="javascript：formcheck();">      
                    <input type="reset" name="Submit2" value="重 置" class="button">
                </td>
                        </tr>
                </body>
            </table>
        </form>
    </body>
</html>