如何知道用户何时关闭浏览器？聊天应用 [英] How to know when user closes browser? Chat application

问题描述

我有一个简单的聊天客户端设置，允许用户使用用户名登录并将他们写入的消息存储在sql数据库中。每3秒钟，数据库就会打印所有行。所以它基本上是一个聊天客户端。

我想保留谁在线的列表。我怎样才能做到这一点？当人们关闭浏览器时，我该如何感觉？

现在我将用户名称作为

  $ name = $ _COOKIE [name]; 
  

如果这个值是空的，我知道他们离开了。但是一旦他们离开了，知道他们的用户名是什么时候已经太迟了，所以我无法追踪到底是谁离开了。

想法？我相当新的PHP，JavaScript和HTML，所以请记住：）

解决方案

表将会有一个名为'lastSeen'的字段，每隔几秒用ajax调用来更新这个字段。

ajax调用可以这样做：

  window.setInterval（function（）{
 $ .ajax（{$ b $ url：_URL_ENGINE +/ updateLastSeen /？userid =+ userID，
 success：function（data）{
 
} 
}）; 
}，2000）; // 2000的意思是2秒
  

现在查询在线玩家列表， p>

  select * from players WHERE lastSeen> DATE_SUB（NOW（），间隔40 SECOND）
  

希望这可以帮助您

I have a simple chat client set up that allows users to login with a username and stores the messages they write in an sql database. Every 3 seconds, the database simply prints of all the rows. So it's basically a chat client.

I'd like to keep a list of who's online. How can I do this? How can I sense when someone has closed the browser?

Right now I'm pulling the username as

$name = $_COOKIE["name"];

and if this value is empty, I know they left. But once they left, it's too late to know what their username was so I can't keep track of who exactly left.

Ideas? I'm fairly new to php, javascript, and html, so keep that in mind :)

解决方案

put online users in a table that will have a field named like 'lastSeen' update this field every few seconds with ajax call..

ajax call be made someting like this :

window.setInterval(function() {
    $.ajax({      
      url: _URL_ENGINE + "/updateLastSeen/?userid=" + userID,
      success: function(data) {

      }
    }); 
}, 2000); // 2000 means 2 seconds

now to query the list of online players u can query them like

select * from players WHERE lastSeen > DATE_SUB(NOW(), interval 40 SECOND) 

hope this helps

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