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

Answer 1

Using jQuery:

$(function() {
    window.isActive = true;
    $(window).focus(function() { this.isActive = true; });
    $(window).blur(function() { this.isActive = false; });
    showIsActive();
});

function showIsActive()
{
    console.log(window.isActive)
    window.setTimeout("showIsActive()", 2000);
}

function doWork()
{
    if (window.isActive) { /* do CPU-intensive stuff */}
}