frontend/js/jquery.appear.js

(function ($) {
    var selectors = []; var check_binded = false; var check_lock = false; var defaults = { interval: 250, force_process: false }
    var $window = $(window); var $prior_appeared; function process() {
        check_lock = false; for (var index = 0; index < selectors.length; index++) {
            var $appeared = $(selectors[index]).filter(function () { return $(this).is(':appeared'); }); $appeared.trigger('appear', [$appeared]); if ($prior_appeared) { var $disappeared = $prior_appeared.not($appeared); $disappeared.trigger('disappear', [$disappeared]); }
            $prior_appeared = $appeared;
        }
    }
    $.expr[':']['appeared'] = function (element) {
        var $element = $(element); if (!$element.is(':visible')) { return false; }
        var window_left = $window.scrollLeft(); var window_top = $window.scrollTop(); var offset = $element.offset(); var left = offset.left; var top = offset.top; if (top + $element.height() >= window_top && top - ($element.data('appear-top-offset') || 0) <= window_top + $window.height() && left + $element.width() >= window_left && left - ($element.data('appear-left-offset') || 0) <= window_left + $window.width()) { return true; } else { return false; }
    }
    $.fn.extend({
        appear: function (options) {
            var opts = $.extend({}, defaults, options || {}); var selector = this.selector || this; if (!check_binded) {
                var on_check = function () {
                    if (check_lock) { return; }
                    check_lock = true; setTimeout(process, opts.interval);
                }; $(window).scroll(on_check).resize(on_check); check_binded = true;
            }
            if (opts.force_process) { setTimeout(process, opts.interval); }
            selectors.push(selector); return $(selector);
        }
    }); $.extend({ force_appear: function () { if (check_binded) { process(); return true; }; return false; } });
})(jQuery);