How do I hook a Javascript function to a page-reload request OR a client-originated websocket disconnect?

154 Views Asked by Matthias Urlichs At 04 April 2025 at 14:11

My problem: my page has a websocket handler. I handle a disconnect event (usually cause by a server restart) by displaying a "server disconnected, please reload" overlay.

However, when the user triggers a reload, the first thing the browser does is to disconnect the socket, which also triggers the disconnect event, so this overlay appears before being replaced by the new page. This is confusing, esp. since reloading the page may take a few seconds.

To clarify, what happens is

user clicks Reload
web socket gets disconnected by the browser
- ws.onclose runs
  - … and displays a "please reload the page" alert overlay (or whatever)
some time passes before the server gets around to assembling the new page
page gets reloaded, overlay vanishes

I want to show that overlay only when the server is the disconnect's originator. Thus I either need to figure out which side did it, or hook into the page reload before it actually happens.

Original Q&A

There are 1 best solutions below

jignesh On 16 December 2016 at 12:34

if(window.performance)

{

    if(performance.navigation.type  == 1 )
          {
            console.log('page reloaded');
          }
}

https://developer.mozilla.org/en-US/docs/Web/API/Navigation_timing_API

Also you can write javascript function and set cookie.

function checkFirstVisit() {
  if(document.cookie.indexOf('mycookie')==-1) {
    // cookie doesn't exist, create it now
    document.cookie = 'mycookie=1';
  }
  else {
    // not first visit, so alert
    alert('You refreshed!');
  }
}

Call on body load event

   <body onload="checkFirstVisit()">

How do I hook a Javascript function to a page-reload request OR a client-originated websocket disconnect?

There are 1 best solutions below

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