JavaScript polling the request server

Source: Internet
Author: User

Question thrown: How does a Web browser maintain communication with a service?

Method One: Ajax polling

Method Two: EventSource polling

Method Three: WebSocket Maintain long connection

The following solution is the combination of Ajax polling and EventSource polling.

Client code:

<!DOCTYPE HTML><HTML><Head>    <Metahttp-equiv= "Content-type"content= "text/html; charset=utf-8"/>    <title></title>    <Scriptsrc= "Jquery.min.js"></Script>    <Scriptsrc= "Pollsource.js"></Script></Head><Body>    <H1>Server Data:</H1>    <DivID= "Serverdata"></Div>    <ahref= "Javascript:Poll.open (+);">Open poll</a>    <ahref= "javascript:Poll.close ();">Close poll</a>    <Scripttype= "Text/javascript">        varServerdata,poll; varServer_url= "index.php"; Window.onload= function() {serverdata=document.getElementById ("Serverdata"); Poll= NewPollsource (Server_url); Poll.onmessage= function(data) {//console.log (data);JSON=json.parse (data); Serverdata.innerhtml=Json.data; }        }    </Script></Body></HTML>

Pollsource.js Code:

/** * pollsource JavaScript Polling server * @param string URL server address Example: www.example.com/index.php * @param json Jsonparam passed to Server parameters * @author Echo*/functionPollsource (url,jsonparam) { This. url =URL;  This. OnMessage =NULL;  This. Resource =NULL;  This. Polltype =typeof(EventSource) = = ' undefined '? ' Ajaxget ': ' EventSource '; //Pass the polling type to the server for the server to respond    if(typeofJsonparam = = ' object ') {jsonparam[' Polltype '] = This.    Polltype; }Else{Jsonparam= {Polltype: This.    Polltype}; }     This. url + = '? ';  for(varIinchJsonparam) {       This. url + = i+ ' = ' +jsonparam[i]+ ' & '; }     This. url = This. url.substring (0, ( This. url.length-1)); /** * Start Polling * @param number spend ajaxget the speed unit is milliseconds*/     This. Open =function(spend) {varOnMessage = This. OnMessage; varURL = This. URL; if(typeofspend = = ' undefined ') spend = 5000; if( This. Polltype = = ' Ajaxget ') {            //Use polling             This. Resource = {};  This. Resource.lockint = SetInterval (function(){                Try{$.get (url,{},function(JSON) {if(typeofOnMessage = = ' function ') OnMessage (JSON);                }); }Catch(e) {alert (e.message);            }},spend);  This. Resource.close =function() {                if(typeof  This. Lockint = = ' Number ') {clearinterval ( This. Lockint); }            }        }Else{            //using server to send event technology             This. Resource =NewEventSource ( This. URL);  This. Resource.onmessage =function(e) {if(typeofOnMessage = = ' function ') OnMessage (e.data); }             This. Resource.onerror =function(e) {if( This. readyState = = 2) alert (' connection not established, or has been closed, or a fatal error has occurred '); }        }    }    /** * Turn off polling*/     This. Close =function() {        if( This. Resource) This. Resource.close (); }}

Service-Side code:

<?PHPHeader("content-type:text/html; Charset=utf-8 ");d Ate_default_timezone_set ("Asia/shanghai");$result=Array(' Code ' =>0, ' msg ' = ' pull success ', ' data ' = ' The current time is: '.Date(' y-m-d h:i:s '));$result= Json_encode ($result);$PollType=isset($_get[' Polltype ']) ?Trim($_get[' Polltype ']) : ‘‘;if($PollType= = ' Ajaxget ') {    //header (' Content-type:application/json; Charset=utf-8 ');    Echo $result;}Else if($PollType= = ' EventSource ') {    Header(' Content-type:text/event-stream '); Echo' Data: '.$result." \ n "; Echo' retry:1000 '. " \ n ";//tell the client to initiate the request 1 seconds at a time    Flush();}Else{     die(' ERROR ');}

Test results:

Code Download: Baidu Network disk

Reference resources:

Https://developer.mozilla.org/zh-CN/docs/Server-sent_events/EventSource
Https://developer.mozilla.org/zh-CN/docs/Server-sent_events/Using_server-sent_events#Event_stream_format

JavaScript polling the request server

Related Article

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.