javascript - 延迟加载效果在我的页面上似乎不起作用

Question

有人对延迟加载有想法。它似乎在我的页面上不起作用。

我做错了什么？

这是我的页面 -> http://500milligrammes.com/fmzz/final/test.html

这是我的 html 部分:

<img class="lazy img-responsive" src="...jpg" data-original="...jpg" alt=""/>

这是我的 js 部分:

$(function() {
$("img.lazy").lazyload({
effect : "fadeIn"
});

这是我的 jquery.lazyload.js 页面:

 /*!
  * Lazy Load - jQuery plugin for lazy loading images
  *
  * Copyright (c) 2007-2015 Mika Tuupola
  *
  * Licensed under the MIT license:
  *   http://www.opensource.org/licenses/mit-license.php
  *
  * Project home:
  *   http://www.appelsiini.net/projects/lazyload
  *
  * Version:  1.9.5
  *
 */

 (function($, window, document, undefined) {
var $window = $(window);

$.fn.lazyload = function(options) {
    var elements = this;
    var $container;
    var settings = {
        threshold       : 0,
        failure_limit   : 0,
        event           : "scroll",
        effect          : "show",
        container       : window,
        data_attribute  : "original",
        skip_invisible  : false,
        appear          : null,
        load            : null,
        placeholder     : "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB/AAffA0nNPuCLAAAAAElFTkSuQmCC"
    };

    function update() {
        var counter = 0;

        elements.each(function() {
            var $this = $(this);
            if (settings.skip_invisible && !$this.is(":visible")) {
                return;
            }
            if ($.abovethetop(this, settings) ||
                $.leftofbegin(this, settings)) {
                    /* Nothing. */
            } else if (!$.belowthefold(this, settings) &&
                !$.rightoffold(this, settings)) {
                    $this.trigger("appear");
                    /* if we found an image we'll load, reset the counter */
                    counter = 0;
            } else {
                if (++counter > settings.failure_limit) {
                    return false;
                }
            }
        });

    }

    if(options) {
        /* Maintain BC for a couple of versions. */
        if (undefined !== options.failurelimit) {
            options.failure_limit = options.failurelimit;
            delete options.failurelimit;
        }
        if (undefined !== options.effectspeed) {
            options.effect_speed = options.effectspeed;
            delete options.effectspeed;
        }

        $.extend(settings, options);
    }

    /* Cache container as jQuery as object. */
    $container = (settings.container === undefined ||
                  settings.container === window) ? $window : $(settings.container);

    /* Fire one scroll event per scroll. Not one scroll event per image. */
    if (0 === settings.event.indexOf("scroll")) {
        $container.bind(settings.event, function() {
            return update();
        });
    }

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

        self.loaded = false;

        /* If no src attribute given use data:uri. */
        if ($self.attr("src") === undefined || $self.attr("src") === false) {
            if ($self.is("img")) {
                $self.attr("src", settings.placeholder);
            }
        }

        /* When appear is triggered load original image. */
        $self.one("appear", function() {
            if (!this.loaded) {
                if (settings.appear) {
                    var elements_left = elements.length;
                    settings.appear.call(self, elements_left, settings);
                }
                $("<img />")
                    .bind("load", function() {

                        var original = $self.attr("data-" + settings.data_attribute);
                        $self.hide();
                        if ($self.is("img")) {
                            $self.attr("src", original);
                        } else {
                            $self.css("background-image", "url('" + original + "')");
                        }
                        $self[settings.effect](settings.effect_speed);

                        self.loaded = true;

                        /* Remove image from array so it is not looped next time. */
                        var temp = $.grep(elements, function(element) {
                            return !element.loaded;
                        });
                        elements = $(temp);

                        if (settings.load) {
                            var elements_left = elements.length;
                            settings.load.call(self, elements_left, settings);
                        }
                    })
                    .attr("src", $self.attr("data-" + settings.data_attribute));
            }
        });

        /* When wanted event is triggered load original image */
        /* by triggering appear.                              */
        if (0 !== settings.event.indexOf("scroll")) {
            $self.bind(settings.event, function() {
                if (!self.loaded) {
                    $self.trigger("appear");
                }
            });
        }
    });

    /* Check if something appears when window is resized. */
    $window.bind("resize", function() {
        update();
    });

    /* With IOS5 force loading images when navigating with back button. */
    /* Non optimal workaround. */
    if ((/(?:iphone|ipod|ipad).*os 5/gi).test(navigator.appVersion)) {
        $window.bind("pageshow", function(event) {
            if (event.originalEvent && event.originalEvent.persisted) {
                elements.each(function() {
                    $(this).trigger("appear");
                });
            }
        });
    }

    /* Force initial check if images should appear. */
    $(document).ready(function() {
        update();
    });

    return this;
};

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

$.belowthefold = function(element, settings) {
    var fold;

    if (settings.container === undefined || settings.container === window) {
        fold = (window.innerHeight ? window.innerHeight : $window.height()) + $window.scrollTop();
    } else {
        fold = $(settings.container).offset().top + $(settings.container).height();
    }

    return fold <= $(element).offset().top - settings.threshold;
};

$.rightoffold = function(element, settings) {
    var fold;

    if (settings.container === undefined || settings.container === window) {
        fold = $window.width() + $window.scrollLeft();
    } else {
        fold = $(settings.container).offset().left + $(settings.container).width();
    }

    return fold <= $(element).offset().left - settings.threshold;
};

$.abovethetop = function(element, settings) {
    var fold;

    if (settings.container === undefined || settings.container === window) {
        fold = $window.scrollTop();
    } else {
        fold = $(settings.container).offset().top;
    }

    return fold >= $(element).offset().top + settings.threshold  + $(element).height();
};

$.leftofbegin = function(element, settings) {
    var fold;

    if (settings.container === undefined || settings.container === window) {
        fold = $window.scrollLeft();
    } else {
        fold = $(settings.container).offset().left;
    }

    return fold >= $(element).offset().left + settings.threshold + $(element).width();
};

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

/* Custom selectors for your convenience.   */
/* Use as $("img:below-the-fold").something() or */
/* $("img").filter(":below-the-fold").something() which is faster */

$.extend($.expr[":"], {
    "below-the-fold" : function(a) { return $.belowthefold(a, {threshold : 0}); },
    "above-the-top"  : function(a) { return !$.belowthefold(a, {threshold : 0}); },
    "right-of-screen": function(a) { return $.rightoffold(a, {threshold : 0}); },
    "left-of-screen" : function(a) { return !$.rightoffold(a, {threshold : 0}); },
    "in-viewport"    : function(a) { return $.inviewport(a, {threshold : 0}); },
    /* Maintain BC for couple of versions. */
    "above-the-fold" : function(a) { return !$.belowthefold(a, {threshold : 0}); },
    "right-of-fold"  : function(a) { return $.rightoffold(a, {threshold : 0}); },
    "left-of-fold"   : function(a) { return !$.rightoffold(a, {threshold : 0}); }
});

})(jQuery, window, document);

Answer 1

第一期:

需要关闭ready函数。

$(function() {
    $("img.lazy").lazyload({
    effect : "fadeIn"
    });
});

第二期:

下面是如何在网站上实现延迟加载的用法:

<img class="lazy" data-original="img/example.jpg" width="640" height="480">

现在，您必须将其存储在数据属性(图像本身)中。您正在做的是在 src 和数据属性中调用图像。现在，当页面加载时，它实际上开始了使用 src 加载图像的过程，然后发生延迟加载。