13.4 错误处理与error对象2.html

javascript即用即差核心对象手册

<form>
   注册帐号
   <input type="text" name="uname" /><br>
   注册密码
   <input type="text" name="upwd" /><br>
   <input type="button" onClick="checkUser()" value="提交">
 </form>
 <br><div id="result"></div>
 <script>
   function checkUser()
   {
      var name=document.forms[0].uname.value;
	  var pwd=document.forms[0].upwd.value;
	  try
	  {
	     if (name.length==0)
		    throw "请填写用户名";
	  }
	  catch(err)
	  {
		 document.getElementById("result").innerHTML+=err+"<br>";
		 do
		   newname=prompt(err,"");
		 while (newname=="")
	  }
	  finally
	  {
	     var renb=/\d+/;
		 var ok=false;
		 //循环执行指导输入密码符合要求位置
	     do
		 {
		    try
	          {
	             if (pwd.length<6 )
		            throw "密码太短";
		            
		          else 
				  {  
				     arr=pwd.match(renb);
				     if (arr[0].length==pwd.length)
		                 throw "密码全为数字，安全级别太低";   
				     else
				         ok=true;
				   }
	            }
	          catch(errinfo)
	            {
	                document.getElementById("result").innerHTML+=errinfo+"<br>";
					errinfo+="请重新输入:";
		            pwd=prompt(errinfo,"");
	             }
		 }while(!ok);
	  }

   }
 </script>