Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource

JavaScript

Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

Behavior

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                <h3 style="margin-left:10px;font-size:12px;font-weight:normal;color:#AAA;"><em>Checks If Browser Tab &amp; Browser Window Gain Or Lose Focus Using The HTML5 Visibility API</em></h3>

<span id="focus" class="active">TAB FOCUS</span> <span id="blur">TAB BLUR</span> <span id="focusW">WINDOW FOCUS</span> <span id="blurW">WINDOW BLUR</span>

<div id="wrapper">
  <div id="box">
    <div id="spot"></div>
  </div>  
</div>

<p><b>To Test</b>: 
  <ol>
    <li> First click inside the Preview panel so the page gains focus ( <strong>very important</strong> )</li>
     <li> Switch between tabs</li>
     <li> Give another program (or one of the CodePen editor panels) focus and come back to the browser</li>
    <li> Look at the above state changes.</li>
  </ol>
</p>


              
            
!

CSS

              
                body{
  background:#555;
  font-family:Arial;
  color:#999;
}

p{
  margin:160px 0 0 20px;
  font-size:12px;
  color:#CCC;
}

ol, ul{
  font-size:12px;
  color:#CCC;
}

span {
  display:inline-block;
  margin:10px; 
  color:#888;
}

span.active {
  color:#FCC30A;
}

#wrapper {
  position:relative;
  margin:30px 0 0 30px;
}

#box {
  position:absolute;
  width:100px;
  height:100px;
  background:#0CB558;
  border-radius:100%;
}

#spot {
  position:relative;
  width:30px;
  height:30px;
  top:2px;
  left:2px;
  background:#FFF;
  border-radius:100%;
}
              
            
!

JS

              
                var $focus = $("#focus"),
    $blur = $("#blur"),
    $focusW = $("#focusW"),
    $blurW = $("#blurW");

// rotate element
var tl = new TimelineMax({paused:true,repeat:-1});

tl.to("#box",1.5,{rotation:360, ease:Linear.easeNone});
tl.play(0);


/////////////////////////////////////////
// main visibility API function 
// check if current tab is active or not
var vis = (function(){
    var stateKey, 
        eventKey, 
        keys = {
                hidden: "visibilitychange",
                webkitHidden: "webkitvisibilitychange",
                mozHidden: "mozvisibilitychange",
                msHidden: "msvisibilitychange"
    };
    for (stateKey in keys) {
        if (stateKey in document) {
            eventKey = keys[stateKey];
            break;
        }
    }
    return function(c) {
        if (c) document.addEventListener(eventKey, c);
        return !document[stateKey];
    }
})();


/////////////////////////////////////////
// check if current tab is active or not
vis(function(){
					
    if(vis()){	
        
        // the setTimeout() is used due to a delay 
        // before the tab gains focus again, very important!
	      setTimeout(function(){ 
          
            // tween resume() code goes here	
            tl.resume();
            
            // add remove active class
            TweenMax.set($focus,{className:'+=active'});
            TweenMax.set($blur,{className:'-=active'});
            TweenMax.set($focusW,{className:'-=active'});
            TweenMax.set($blurW,{className:'-=active'});
          
        },300);		
												
    } else {
	
        // tween pause() code goes here	
        tl.pause();
        
        // add remove active class
        TweenMax.set($blur,{className:'+=active'});
        TweenMax.set($focus,{className:'-=active'});
        TweenMax.set($focusW,{className:'-=active'});
        TweenMax.set($blurW,{className:'-=active'});
    }
});


/////////////////////////////////////////
// check if browser window has focus		
var notIE = (document.documentMode === undefined),
    isChromium = window.chrome;
      
if (notIE && !isChromium) {

    // checks for Firefox and other  NON IE Chrome versions
    $(window).on("focusin", function () { 
        
        setTimeout(function(){      
            
            // tween resume() code goes here
            tl.resume();
          
            // add remove active class
            TweenMax.set($focusW,{className:'+=active'});
            TweenMax.set($blurW,{className:'-=active'});
            TweenMax.set($focus,{className:'-=active'});
            TweenMax.set($blur,{className:'-=active'});
          
        },300);

    }).on("focusout", function () {

        // tween pause() code goes here
        tl.pause();
      
        // add remove active class
        TweenMax.set($blurW,{className:'+=active'});
        TweenMax.set($focusW,{className:'-=active'});
        TweenMax.set($focus,{className:'-=active'});
        TweenMax.set($blur,{className:'-=active'});

    });

} else {
    
    // checks for IE and Chromium versions
    if (window.addEventListener) {

        // bind focus event
        window.addEventListener("focus", function (event) {
          
            setTimeout(function(){                 
                 
                 // tween resume() code goes here
                 tl.resume();
              
                 // add remove active class
                 TweenMax.set($focusW,{className:'+=active'});
                 TweenMax.set($blurW,{className:'-=active'});
                 TweenMax.set($focus,{className:'-=active'});
                 TweenMax.set($blur,{className:'-=active'});
              
            },300);

        }, false);

        // bind blur event
        window.addEventListener("blur", function (event) {

            // tween pause() code goes
            tl.pause();
          
            // add remove active class
            TweenMax.set($blurW,{className:'+=active'});
            TweenMax.set($focusW,{className:'-=active'});
            TweenMax.set($focus,{className:'-=active'});
            TweenMax.set($blur,{className:'-=active'});

        }, false);

    } else {

        // bind focus event
        window.attachEvent("focus", function (event) {

            setTimeout(function(){                 

                 // tween resume() code goes here
                 tl.resume();
               
                 // add remove active class
                 TweenMax.set($focusW,{className:'+=active'});
                 TweenMax.set($blurW,{className:'-=active'});
                 TweenMax.set($focus,{className:'-=active'});
                 TweenMax.set($blur,{className:'-=active'});
              
            },300);

        });

        // bind focus event
        window.attachEvent("blur", function (event) {

            // tween pause() code goes here
            tl.pause();
          
            // add remove active class
            TweenMax.set($blurW,{className:'+=active'});
            TweenMax.set($focusW,{className:'-=active'});
            TweenMax.set($focus,{className:'-=active'});
            TweenMax.set($blur,{className:'-=active'});

        });
    }
}
              
            
!
999px

Console