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parallax.js
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parallax.js
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/*
* Super Simple Parallax Jquery Plugin
* John Tajima
*
*/
(function($) {
$.fn.parallax = function(options) {
var opts = $.extend({}, $.fn.parallax.defaults, options);
var prevPos = 0; // start pos at 0
// init all data-scrollFactor elements and store orig pos & start/stop and factor
var $layers = $("[data-scrollFactor]");
// cache some data in each layer
$layers.each(function(i,el){
$(el).data({
origPos: $(el).position().top,
scrollFactor: $(el).attr('data-scrollFactor'),
scrollStart: $(el).attr('data-scrollStart'),
scrollEnd: $(el).attr('data-scrollEnd')
});
});
// listen to scrolling
$(this).scroll(function(e){
var currPos = $(this).scrollTop(); // get scroll pos
log("curr: "+currPos);
var delta = currPos - prevPos;
// loop through all layers
$layers.each(function(i,el){
var params = $(el).data();
// calculate newPos for layer
var newPos = params.origPos - currPos;
// add/sub back in scroll range
if (currPos > params.scrollEnd) {
var amt = params.scrollEnd - params.scrollStart;
} else if (currPos > params.scrollStart) {
var amt = currPos - params.scrollStart;
} else {
var amt = 0;
}
newPos += amt * params.scrollFactor;
$(el).css({'top': newPos+"px"}); // move layer
//$(el).animate({'top':newPos+"px"}, 10);
});
prevPos = currPos;
});
return this;
};
$.fn.parallax.defaults = {};
/* private functions */
function log(msg) {
if (window.debug === true && console && console.log) {
console.log(msg);
}
}
})(jQuery);