// JavaScript Document

/* 
start of display next, previous pages -  javascript 
*/

//declare an array variable
var hyperlinks=new Array();

// initialize variable which will decide whether to load previous page or home page.
var pageprevious="page";

//add values to an array
hyperlinks=["projectsUrbanHabitat.html", // Urban Habitat
			"projectsWilliamsburg2.html", // Williamsburg Loft
			"projectsDinnerstein.html", //Dinnerstein
			"projectsTeddy.html", // Teddy’s Bar & Grill
			"projectsW77.html", // P20 West 77    
			"projectsHamlin.html", // 333 East 66
		    "projectsC2C.html", // C2C
			"projectsTwoFamily.html", // Two Family House
			"projectsBirthCenter.html",	// Birth Center	
			"projectsPowerPlant.html", // Ame Powerplant
			"projectsUrbanLagoon.html", // Urban Lagoon
			"projectsChase.html", // Chase-McNamara						
			"projectsHirotaJackall.html",// Hirota-Jackall
			]; 

//retrieve length of array
var ArrCount=hyperlinks.length;

// function to load next page.
function loadNext()
{	
	//retrieving index of the current page in array
	indexval=getIndex();
	
	//checking for indexval
	if(indexval != "fail" && indexval<ArrCount-1)
	{
		//incremnting the indexval
		indexval=indexval+1;	

		//calling corresponding file from the array
		location.href=hyperlinks[indexval];
	}
}

// function to load previous page or home page.
function loadPrevious()
{
	
	//retrieving index of the current page in array
	indexval=getIndex();

	//checking for indexval
	if(indexval != "fail" && indexval>0)
	{
		//decrementing the indexval
		indexval=indexval-1;

		// check whether to display previous page or home page
		if(pageprevious=='page')
		{
			//load corresponding file from the array
			location.href=hyperlinks[indexval];
		}
		else
		{
			//load the home page
			location.href=hyperlinks[0];
		}
	}
}


// function which returns the index of the current page in the array.
function getIndex()
{
// split the current url and store in a array
var page_url = (location.href).split("/");

//get the name of the file.
var pagename=page_url[page_url.length-1];

	//traverse through array to get the indexval of the pagename
	for(index=0;index<ArrCount;index++)
	{
		//check for the pagename
		if(hyperlinks[index]==pagename)
		{
			//return index value			
			return index;
		}
	}
	// if the page does not exist in the array return fail
	return "fail";
}

/* 
end of display next, previous pages -  javascript 
*/