如何使用jquery ajax向php页面发送异步请求

问题描述：

i am new to web development creating a kind of social networking website for college project. I want to include update the messages count in the message menu every time there is a new msg in the database for the user(like facebook message menu on homepage)

But it's frustrating learning ajax, however after searching on web and reading some topics from some books I came to the solution that i can make an $ajax call in my js file in the homepage and send data ('name'=>'user') stored in javascript cookie that i have created on loading of home page after the user login, to a php file which will search across the recent_msg table in database to fetch the recent message for the logged in user if any after fetching the php file will create the html file with code snippet and further another jquery code will append that snippet from file to the message list menu.

the PHP part is not the problem but how can i send the username to the php file using jquery ajax api, here is the code what i think i can apply but i am doubtful in that if this is the correct way

$(document).ready(function{

setInterval ( function()
{
    var usr = getCookie("name");
    $.ajax ( {
        url: '/phpScripts/recent_msg.php',
        type: 'POST',
        data: usr,
        success: function(data){

             }
        } );
},10);
});

what is the purpose of success function in the code?

我是网络开发的新手，为大学项目创建了一种社交网站。我想在每次数据库中为用户提供新的消息时包括更新消息菜单中的消息计数（如主页上的facebook消息菜单） p>

但是学习ajax令人沮丧，然而，在网上搜索并从一些书籍中读取一些主题后，我找到了解决方案，我可以在主页的js文件中进行$ ajax调用并发送数据（'name'=＆gt;'user'）存储在我在用户登录后加载主页时创建的javascript cookie中，到一个php文件，它将搜索数据库中的recent_msg表，以获取登录用户的最新消息（如果有的话，在获取php之后） file将使用代码片段创建html文件，并且另一个jquery代码会将该片段从文件追加到消息列表菜单。 p>

PHP部分不是问题，但我如何发送使用jquery ajax api的php文件的用户名，这里是我认为我可以应用的代码，但我怀疑如果这是相关的 ct way p>


  $（document）.ready（function {
 
setInterval（function（）
 {
 var usr = getCookie（“name”）; 
  $ .ajax（{
 url：'/phpScripts/recent_msg.php'，
n type：'POST'，
 data：usr，
 success：function（data）{
 
} 
}）  ; 
}，10）; 
}）; 
  code>  pre> 
 
 代码中成功函数的目的是什么？ p> 
  div  >

答

data needs to be in the form of an object / key-value-pair (EDIT: or if a string, as a valid querystring). data: { name: usr }. However, since it's in a cookie, your PHP page will have direct access to that cookie. It's safer to let your session cookie tel the PHP page who the user is instead of relying on an AJAX call to tell the PHP page who it is.

http://php.net/manual/en/features.cookies.php

So I'd drop data from your AJAX call altogether, and in your PHP page, use $_COOKIE["name:"]

Then whatever HTML gets passed back from the PHP page will arrive in the data call. If it's HTML, then simply add it to your HTML to some message div, such as.

<div id="recent-messages"></div>

<script type="text/javascript">
$(document).ready(function{

setInterval ( function()
{
    var usr = getCookie("name");
    $.ajax ( {
        url: '/phpScripts/recent_msg.php',
        type: 'POST',
        data: usr,
        success: function(data){
                $('#recent-messages').html(data);
             }
        } );
},10);
});
</script>

答

The success function executes whenever your ajax call completes successfully. This means that the page actually exists and no server-side errors occurred on the page. The variable data will contain whatever information is returned from the page on the sever /phpScripts/recent_msg.php. Generally this is either json or xml, but it entirely depends on your implementation of recent_msg.php.

答

If the user has to log in that means you have to have created a session. In that case you can store the logged in user's information such as their name in $_SESSION on the server and there is no need to store it as a cookie. Since $_SESSION is already on the server, there is no need to send that data via ajax in any case.

如何使用jquery ajax向php页面发送异步请求

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