Opacity on scroll

Opacity on scroll

var animation_start_pos = 0, animation_end_pos = 1000; //where you want the animation to stop

$(document).scroll(function() {
    var scroll_pos = $(this).scrollTop(); 
        var percentScrolled = parseFloat(scroll_pos/animation_end_pos);
        jQuery('.people-opacity').css('opacity',  percentScrolled );
});

html //
<div class="people-opacity" style="opacity: 0;"></div>

css//
.people-opacity {
	background: #fff;
	left: 0;
	top: 0;
	opacity: 0;
	height: 100%;
	width: 100%;
	transition: .3s;
	position: absolute;
}