// Function to call the plugin and the callers AFTER DOM load
function pluginload()  {
// The plugin code
// Known issues and behaviours: 
// IOS fires y scroller position only on touchcancel which causes stuttering.
// Stuttering under Android 4.x is hardware related, chrome works smoother
// Windows Phone 7 same as iOS, Windows Phone 8 same as Android
(function($){
	// Creates new Function "parallax" that receives up to three inputs (start, stop, coeff)
    $.fn.parallax = function(input){
		// New var is the targetet element
        var targetelement = $(this);
		// Get "targetelement" coordinates relative to document
        offset = targetelement.offset();
        // Create object containing four vars
		var defaults = {
            "start": 0, // Where the element should begin to scroll in px, not recommended
            "stop": offset.top + targetelement.height(), // Where the element shall stop scrolling in px, not recommended
            "coeff": 1, // Scroll speed (1 is default), can be + or -
			"delay": 0 // Instead of "start", when the element should start scrolling in px
        };
		// Handle default and input options, .extend merges to objects together to new object "opts", first object "defaults" is overwritten by second object with user input "input"
        var opts = $.extend(defaults, input);
		// freaking magic
        return this.each(function(){
			// more magic
            $(window).bind('scroll', function() {
				// new var "windowTop" is the difference between the current vertical position of the scrollbar "scrollTop" and user defined "delay"
                windowTop = $(window).scrollTop()-defaults.delay/*+150*/; // real start delay
                // if "targetelement" is between user defined start and stop, apply animation
				if((windowTop >= opts.start) && (windowTop <= opts.stop)) {
					// var "newCoord" defines the new coordinates for "targetelement" and is created by multiplying the current vertical position of the scrollbar with user defined animation speed 
                    newCoord = windowTop * opts.coeff;
					// Apply the new coordinates to "targetelement" css "background-position"
                    targetelement.css({
                        "background-position": "0 "+ newCoord + "px"
                    });
                }
            });
        });
    };
})(jQuery);

// call the plugin for any desired element (call with .class)
$('.element1').parallax({ "coeff":2, "delay":0 });
$('.element3').parallax({ "coeff":1.2, "delay":0 });
$('.element2').parallax({ "coeff":4.55, "delay":0 });
$('.element4').parallax({ "coeff":0.2, "delay":1200 });
$('.element5').parallax({ "coeff":1.2, "delay":1200 });
$('.element6').parallax({ "coeff":2.2, "delay":1200 });
$('.element7').parallax({ "coeff":-0.2, "delay":2400 });
$('.element8').parallax({ "coeff":-1.2, "delay":2400 });
$('.element9').parallax({ "coeff":8, "delay":2400 });
}