JavaScript: RegExp check UserName

Function ： We can use regular expressions to check user input data formats.

Homework： Check user input meets the requirements or not.

I use regular expressions to check the users Chinese name , nickname and their phonenumber.

This is this projiect's appearance:

Below is this project's code:

 <!DOCTYPE html>
 <html lang="en">
 <head>
     <meta charset="UTF-8">
     <title>Document</title>
 </head>
 <script>
         function user(){
             var user=document.getElementById("user").value;
             var User=/[\u4e00-\u9fa5]{2,5}/;
             if(User.test(user)) alert("格式正确");
             else alert("格式错误");
         }
         function Name(){
             var name=document.getElementById("Name").value;
             var Name=/^[a-zA-z][a-zA-Z0-9_]{2,9}$/;
             if(Name.test(name)) alert("格式正确");
             else alert("格式错误");
         }
         function Phone(){
             var phone=document.getElementById("Phone").value;
             var Phone=/^[+]{0,1}(\d){1,3}[ ]?([-]?((\d)|[ ]){4,12})+$/;
             if(Phone.test(phone)) alert("格式正确");
             else alert("格式错误");
         }
     </script>
  <body>
         用户名：<input type="text" name="user" id="user">
         <input type="button" value="检查" onclick="user()"><br>要求:两个中文字符以上<br><br>
         昵&nbsp;&nbsp;&nbsp;称：<input type="text" name="Name" id="Name">
         <input type="button" value="检查" onclick="Name()"><br>要求:字母开头的3-10位昵称,可含有字母或下划线<br><br>
         手机号：<input type="text" name="Phone" id="Phone" >
         <input type="button" value="检查" onclick="Phone()"><br>要求:5位数字以上
 </body>
 </html>