How to tell if browser/tab is active [duplicate]

Answer 1

I would try to set a flag on the window.onfocus and window.onblur events.

The following snippet has been tested on Firefox, Safari and Chrome, open the console and move between tabs back and forth:

var isTabActive;

window.onfocus = function () { 
  isTabActive = true; 
}; 

window.onblur = function () { 
  isTabActive = false; 
}; 

// test
setInterval(function () { 
  console.log(window.isTabActive ? 'active' : 'inactive'); 
}, 1000);

Try it out here.