jquery.lazyload.js 圖片延遲加載

 jQuery頁面圖片伴隨滾動條逐漸顯示 
根據實際應用可以進行相應的修改

// 天涯版
(function(jQuery) {


jQuery.fn.lazyload = function(options) {
    var settings = {
        threshold    : 0,
        failurelimit : 0,
        event        : "scroll",
        effect       : "show",
        container    : window
    };

    if(options) {
        jQuery.extend(settings, options);
    }

    /* Fire one scroll event per scroll. Not one scroll event per image. */
    var elements = this;
    if ("scroll" == settings.event) {
        jQuery(settings.container).bind("scroll", function(event) {

            var counter = 0;
            elements.each(function() {
                if (jQuery.abovethetop(this, settings)) {
                        /* Nothing. */
                } else if (!jQuery.belowthefold(this, settings)) {
                        jQuery(this).trigger("appear");
                } else {
                    if (counter++ > settings.failurelimit) {
                        return false;
                    }
                }
            });
            /* Remove image from array so it is not looped next time. */
            var temp = jQuery.grep(elements, function(element) {
                return !element.loaded;
            });
            elements = jQuery(temp);
        });
    }

    this.each(function() {
        var self = this;

        /* Save original only if it is not defined in HTML. */
        if (undefined != jQuery(self).attr("original")){
            self.loaded = false;

            /* When appear is triggered load original image. */
            jQuery(self).one("appear", function() {
                if (!this.loaded) {
                    jQuery("<img />")
                        .bind("load", function() {
                            jQuery(self)
                                .hide()
                                .removeAttr("height")
                                .attr("src", jQuery(self).attr("original"))
                                [settings.effect](settings.effectspeed);
                            self.loaded = true;
                        })
                        .attr("src", jQuery(self).attr("original"));
                };
            });
        }
    });

    /* Force initial check if images should appear. */
    jQuery(settings.container).trigger(settings.event);

    return this;
};

/* Convenience methods in jQuery namespace.           */
/* Use as  jQuery.belowthefold(element, {threshold : 100, container : window}) */

function checkshow(){


}

jQuery.belowthefold = function(element, settings) {
    if (settings.container === undefined || settings.container === window) {
        var fold = jQuery(window).height()*2 + jQuery(window).scrollTop();
    } else {
        var fold = jQuery(settings.container).offset().top + jQuery(settings.container).height()*2;
    }       
    return fold <= jQuery(element).offset().top - settings.threshold;

};

jQuery.abovethetop = function(element, settings) {
    if (settings.container === undefined || settings.container === window) {
        var fold = jQuery(window).scrollTop();
    } else {
        var fold = jQuery(settings.container).offset().top;
    }
    return fold >= jQuery(element).offset().top + settings.threshold  + jQuery(element).height();
};
/* Custom selectors for your convenience.   */
/* Use as jQuery("img:below-the-fold").something() */

jQuery.extend(jQuery.expr[':'], {
    "below-the-fold" : "jQuery.belowthefold(a, {threshold : 0, container: window})",
    "above-the-fold" : "!jQuery.belowthefold(a, {threshold : 0, container: window})"
});


})(jQuery);
jQuery("#pContentDiv .post img[original]").lazyload({
    effect:"fadeIn"
});</pre>