My parallax secret

parallax-secret.js

/*########################################################################*/
/*###### using jQuery selector for a fast/cross-browser resolution #######*/
/*########################################################################*/
var totalAreas = 6,  // this value is obviously arbitrary
	winH = $(window).height,  // the window height
	top = $(window).scrollTop(), // the current scroll value
	maxScroll = $(document).height() - winH, // the maximum scroll value
	scrollPerc = top/maxScroll, // the current scroll percentage
	areaPercent = 0; // init variable

// just logging the percentage, from here is up to you
function logPercent(index, percent) {
	console.log("Area index: "+index+" is "+percent+"%. Calculate proportions!");
}

/* calculate the percentage from each area */
for(var i = 0; i < totalAreas; i++){//#########  here is the catch: the percent of the total scroll times the total of areas minus the current index, plus one :)
	areaPercent = 1 + ((scrollPerc * totalAreas) - i); 
	logPercent(i, areaPercent); // loggin result
}

//######################################################################
//##### PS: Assuming the areas has the same height, the window height 

LIVE EXAMPLE AT: www.fullsocialwifi.com.br

LIVE EXAMPLE AT: www.fullsocialwifi.com.br