Is it possible to link progressive web app to toast

Question

I have code for a toast like below.

html

<button onclick="launch_toast()">Show Toast</button>

<div id="toast"><div id="img">Icon</div><div id="desc">A notification message..</div></div>

css

#toast {
    visibility: hidden;
    max-width: 50px;
    height: 50px;
    /*margin-left: -125px;*/
    margin: auto;
    background-color: #333;
    color: #fff;
    text-align: center;
    border-radius: 2px;

    position: fixed;
    z-index: 1;
    left: 0;right:0;
    bottom: 30px;
    font-size: 17px;
    white-space: nowrap;
}
#toast #img{
    width: 50px;
    height: 50px;

    float: left;

    padding-top: 16px;
    padding-bottom: 16px;

    box-sizing: border-box;


    background-color: #111;
    color: #fff;
}
#toast #desc{


    color: #fff;

    padding: 16px;

    overflow: hidden;
    white-space: nowrap;
}

#toast.show {
    visibility: visible;
    -webkit-animation: fadein 0.5s, expand 0.5s 0.5s,stay 3s 1s, shrink 0.5s 2s, fadeout 0.5s 2.5s;
    animation: fadein 0.5s, expand 0.5s 0.5s,stay 3s 1s, shrink 0.5s 4s, fadeout 0.5s 4.5s;
}

@-webkit-keyframes fadein {
    from {bottom: 0; opacity: 0;} 
    to {bottom: 30px; opacity: 1;}
}

@keyframes fadein {
    from {bottom: 0; opacity: 0;}
    to {bottom: 30px; opacity: 1;}
}

@-webkit-keyframes expand {
    from {min-width: 50px} 
    to {min-width: 350px}
}

@keyframes expand {
    from {min-width: 50px}
    to {min-width: 350px}
}
@-webkit-keyframes stay {
    from {min-width: 350px} 
    to {min-width: 350px}
}

@keyframes stay {
    from {min-width: 350px}
    to {min-width: 350px}
}
@-webkit-keyframes shrink {
    from {min-width: 350px;} 
    to {min-width: 50px;}
}

@keyframes shrink {
    from {min-width: 350px;} 
    to {min-width: 50px;}
}

@-webkit-keyframes fadeout {
    from {bottom: 30px; opacity: 1;} 
    to {bottom: 60px; opacity: 0;}
}

@keyframes fadeout {
    from {bottom: 30px; opacity: 1;}
    to {bottom: 60px; opacity: 0;}
}

js

function launch_toast() {    
  var x = document.getElementById("toast");   
  x.className = "show";    
  setTimeout(function(){ 
    x.className = x.className.replace("show", ""); 
  }, 5000); 
}

I want to know how to link this code to my progressive web app so that on clicking the user is able to download the PWA. My site.

Answer 1

You should get a reference to the beforeinstallpromt event, on which you can call the promt function later on in your toast. You can get this event by adding an event listener as follows (source: Google):

let installPromptEvent;

window.addEventListener('beforeinstallprompt', (event) => {
  // Prevent Chrome <= 67 from automatically showing the prompt
  event.preventDefault();
  // Stash the event so it can be triggered later.
  installPromptEvent = event;
  // Update the install UI to notify the user app can be installed
  document.querySelector('#install-button').disabled = false;
});

Hence, in your launch_toast function, you can launch the prompt:

function launch_toast(){
  installPromptEvent.prompt();
}

This is, of course, assuming that your manifest is configured well and that your service worker could also be registered. If the device does not support this, the beforeinstallprompt will not be fired and your reference to installPromptEvent will be undefined. The event will also not fire when the PWA is already installed on the device.