Keeping connection alive in Javascript / XMLHttpRequest

Question

Iam building an application that listens to an internal connection of a certain external url and insert its internally loaded content to a new page at my end.

My statement above might sound confusing but a good analogue of the external url are Instagram stories when you visit this external site, it loads complete in the browser (the rolling icon stops, but this doesn't stop the request of unseen updates )

I have built a JavaScript server using nodejs running on npm and have set the content header

Am also using htaccess to make it stay alive so that I can listen and load new internal connection

Header set Connection keep-alive>

but doesn't seems to work

    if(err){

        if(err == 'ENOENT'){
            res.writeHead(404, {'Content-Type' : 'text/html'});
            res.write(path.join(__dirname, 'public', '404.html'));
            res.end();

        }else{
            res.writeHead(500, {'Content-Type' : 'text/html'});
            res.write('<enter><h1>Some server error just occured .... </h1></center>');
            res.end();
        }

    }else{
        res.writeHead(200, {'Content-Type' : contentType, 'Connection':' keep-alive', 'Transfer-Encoding':' chunked', 'Accept':' */*', 'User-Agent':' Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36'});
        res.write(content);
        res.end();
    }

Am expecting to get the new loaded content each time a connection runs underground without reloading the browser and again just like scrolling through Instagram status / stories

If your server is running `nodejs`, why did you tag `PHP` ? – Accountant م Aug 23 '19 at 18:10 — Accountant م, Aug 23 '19 at 18:10

Seth B · Answer 1 · 2019-08-23T19:26:30.617

0

I think this is the wrong approach. You could just have it check every 5 seconds to see if there is something new on the client side.

function checkURL(){
    var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function() {
        if (this.readyState == 4 && this.status == 200) {
            document.write(this.responseText);
        }
    };
    xhttp.open("GET", "https://example.com/", true);
    xhttp.send();
}
setInterval(checkURL,5000); //5000 = 5 seconds

If you must do it in Node.JS, take a look at this post: HTTP keep-alive in node.js

edited Aug 23 '19 at 19:26

answered Aug 23 '19 at 18:01

Seth B

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I have done exactly that also but it loads just the first page of the url and then ends the connection – Nob Music Aug 23 '19 at 18:05
Can you give a little more context of your project? – Seth B Aug 23 '19 at 18:06
when you visit instagram.com/stories/@username/ it loads the first page with the first connection (if you are using the xmlhttprequest to fetch the content it returns a page which has just the site logo) then stops and loads the rest through what I believe to be xmlhttprequest – Nob Music Aug 23 '19 at 18:15
not all but it only returns the content from the first established connection – Nob Music Aug 23 '19 at 18:23
How much data is the content? – Seth B Aug 23 '19 at 20:22

Keeping connection alive in Javascript / XMLHttpRequest

1 Answers1