My function window.onblur, not working with external links

Question

I have the following problem, when I open a link of my host, my function to detect the loss of focus works fine, but when I execute an external link, it does not work ... why does this happen?

var myWindow = window.open(' https://www.google.com.ar ');

myWindow.onblur = function(){ alert('myWindow lost focus'); }

I'm just looking to know if the open external link is observed or not!

Answer 1

You can add an event listener for the visibilitychange event of the document of the opened window.

myWindow.document.addEventListener('visibilitychange', function(event){
    if(this.hidden){
        alert('myWindow is hidden');
    }
});

JSFiddle Demo: https://jsfiddle.net/r3hvet8m/