隐藏在底部的DIV点击弹出jquery特效

隐藏在底部的DIV点击弹出jquery特效

(function($) {

$.belowthefold = function(element, settings) {
var fold = $(window).height() + $(window).scrollTop();
return fold <= $(element).offset().top - settings.threshold;
}; $.abovethetop = function(element, settings) {
var top = $(window).scrollTop();
return top >= $(element).offset().top + $(element).height() - settings.threshold;
};

$.rightofscreen = function(element, settings) {
var fold = $(window).width() + $(window).scrollLeft();
return fold <= $(element).offset().left - settings.threshold;
};

$.leftofscreen = function(element, settings) {
var left = $(window).scrollLeft();
return left >= $(element).offset().left + $(element).width() - settings.threshold;
};

$.inviewport = function(element, settings) {
return !$.rightofscreen(element, settings) && !$.leftofscreen(element, settings) && !$.belowthefold(element, settings) && !$.abovethetop(element, settings);
};

$.extend($.expr[':'], {
"below-the-fold": function(a, i, m) {
return $.belowthefold(a, {threshold : 0});
},
"above-the-top": function(a, i, m) {
return $.abovethetop(a, {threshold : 0});
},
"left-of-screen": function(a, i, m) {
return $.leftofscreen(a, {threshold : 0});
},
"right-of-screen": function(a, i, m) {
return $.rightofscreen(a, {threshold : 0});
},
"in-viewport": function(a, i, m) {
return $.inviewport(a, {threshold : 0});
}
});
})(jQuery);