$.extend($.fn.validatebox.defaults.rules, { 
minLength: { 
validator: function(value, param){ 
return value.length >= param[0]; 
}, 
message: 'Please enter at least {0} characters.' 
} 
}); 

<div id="userReg" class="easyui-panel" style="width:400px; height:300px;" title="注册用户"> 
<form action="" method="post"> 
<table> 
<tr> 
<td>用户名:</td> 
<td><input type="text" name="username" class="easyui-validatebox" required=true 
validType="midLength[4,10]" value=""/></td> 
</tr> 
<tr> 
<td>密码:</td> 
<td><input type="text" name="password" class="easyui-validatebox" required=true validType="pwdLength[8]" value=""/></td> 
</tr> 
<tr> 
<td>性别:</td> 
<td> 
<input type="radio" name="sex" checked="checked" value="male"/>男 
<input type="radio" name="sex" value="female"/>女 
</td> 
</tr> 
<tr> 
<td>年龄:</td> 
<td><input type="text" name="age" value=""/></td> 
</tr> 
<tr> 
<td>出生日期:</td> 
<td><input type="text" name="birth" value=""/></td> 
</tr> 
<tr> 
<td>所属城市:</td> 
<td><input type="text" name="city" value=""/></td> 
</tr> 
<tr> 
<td>薪水:</td> 
<td><input type="text" name="salary" value=""/></td> 
</tr> 
<tr> 
<td colspan="2"> 
<a class="easyui-linkbutton">保存</a> 
</td> 
</tr> 
</table> 
</form> 
</div> 
<script type="text/javascript"> 
$(function(){ 
$.extend($.fn.validatebox.defaults.rules,{ 
midLength:{ 
validator:function(value, param){ 
return value.length >= param[0] && value.length<=param[1]; 
}, 
message: '用户名必须在4到10位之间!' 
}, 
pwdLength:{ 
validator:function(value,param){ 
return value.length==param[0]; 
}, 
message:'密码必须是8位' 
} 
}); 
}); 
</script>