Simple prefetch functionality (ifvisible.js)

config:
[labs]
allow_prefetch

vendors/ifvisible/README.md

@@ -0,0 +1,102 @@
+ifvisible.js
+------------
+
+Crosbrowser & lightweight way to check if user is looking at the page or interacting with it.
+
+#### Check out the [Demo](http://serkanyersen.github.com/ifvisible.js/demo.html) or read below for code example or Check [Annotated Sorce](http://serkanyersen.github.com/ifvisible.js/docs/ifvisible.html)
+
+
+## Installation
+From Bower
+```
+bower install ifvisible
+```
+
+For Meteor
+```
+mrt add ifvisible
+```
+> meteor package is provided by [@frozeman](https://github.com/frozeman/meteor-ifvisible.js) via [Atmosphere](https://atmosphere.meteor.com/package/ifvisible)
+
+## Examples
+
+```javascript
+
+// If page is visible right now
+if( ifvisible.now() ){
+	// Display pop-up
+	openPopUp();
+}
+
+```
+
+Handle tab switch or browser minimize states
+
+```javascript
+
+ifvisible.on("blur", function(){
+	// example code here..
+	animations.pause();
+});
+
+ifvisible.on("focus", function(){
+	// resume all animations
+	animations.resume();
+});
+
+```
+
+ifvisible.js can handle activity states too, such as being IDLE or ACTIVE on the page
+
+```javascript
+
+ifvisible.on("idle", function(){
+	// Stop auto updating the live data
+	stream.pause();
+});
+
+ifvisible.on("wakeup", function(){
+	// go back updating data
+	stream.resume();
+});
+
+```
+
+Default idle duration is 60 seconds but you can change it with `setIdleDuration` method
+
+```javascript
+
+ifvisible.setIdleDuration(120); // Page will become idle after 120 seconds
+
+```
+
+You can manually trigger status events by calling them directly or you can set events with their names by giving first argument as a callback
+
+```javascript
+
+ifvisible.idle(); // will put page in a idle status
+
+ifvisible.idle(function(){
+	// This code will work when page goes into idle status
+});
+
+// other methods are
+ifvisible.blur();
+ifvisible.focus();
+ifvisible.idle();
+ifvisible.wakeup();
+
+```
+
+You can set your smart intervals with ifvisible.js, if user is IDLE or not seeing the page the interval will automatically stop itself
+
+```javascript
+
+// If page is visible run this function on every half seconds
+ifvisible.onEvery(0.5, function(){
+    // Do an animation on the logo only when page is visible
+	animateLogo();
+
+});
+
+```