Inject link and redirect for specific slide for Wordpress NextGEN gallery

ngglinkinject.js

window.requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;

/**
* Inject link and redirect for specific slide for Wordpress NextGEN gallery 
* (c) 2013 Code Lens | Jakub Gadkowski
* Licenced under Creative Commons Attribution 4.0 International Public License  http://creativecommons.org/licenses/by/4.0/
*/

window.addEventListener('load', function(){
	
	var CLtimeLast = Date.now(); //create initial timestamp
	var CLtestedSLider = document.getElementById('slider'); //monitoring this element
	var CLstateIndicator = 1; //starting from the first slide so we need it on
	
	//start checks only if monitored element exist
	if (CLtestedSLider) {
	
		function CLupdateSlider(internalCheck){
			//if we are on the right slide and new styles has not been applied
			if (CLstateIndicator === 1 && internalCheck === 1 ) {
				//apply new style and add 'click' listener
				CLtestedSLider.style.cursor = 'pointer';
				CLtestedSLider.addEventListener('click',CLredirect);
				//reset indicator so it will not fire again on this slide 
				CLstateIndicator = 0;		
			}else if (CLstateIndicator === 0 && internalCheck === 0) {
				//remove style and remove eventListener
				CLtestedSLider.style.cursor = 'default';
				CLtestedSLider.removeEventListener('click',CLredirect);
				//reset indicator, it will fire when righ slide shows again
				CLstateIndicator = 1;
			}
		}
	
		function CLredirect(){
			window.open('http://putyourlinkhere');
		}
	
		//do the check using rAF - less resources needed than setInterval
		function CLcheckSlider(){
			//calculate delta
			var dateNow = Date.now();
			var delta = dateNow - CLtimeLast;
	
			//do the heavy check only once per second
			if (delta >= 1000){
				CLtimeLast = dateNow;
				// the [0] corresponds with the first slide, the second will be [1], third = [2]
		        var CLelementTest = CLtestedSLider.getElementsByClassName('nivo-control')[0].classList.contains('active');
		        //if we are on the right slide fire up style changes 
		        if ( CLelementTest ){
					CLupdateSlider(1);
		        }else {
		        	//or tell the CLupdateSlider to revert changes
		        	CLupdateSlider(0);
		        }
			}
			//schedule next rAF
			requestAnimationFrame(CLcheckSlider);
		}
	
		//fire up first rAF
		requestAnimationFrame(CLcheckSlider);
	}
});