代码重构 - Javascript Infinite Scroll，如何重构这一段代码

Question

用途

当用户手机 scroll 的时候，自动加载分页中的内容。如何让下面这一段代码更优美

代码

javascript//网址：http://xxx.com/game/top-hot/p/1/
//需要先引入 jquery.min.js 库
    var pageAutoLoad = [];
    pageAutoLoad.page = 1 || 1;
    pageAutoLoad.pageTotal = 2 || 1;
    pageAutoLoad.nextUrl = "\/game\/top-hot\/p\/PAGE\/" || '';
    pageAutoLoad.selector = {
        content: '.list_game ul',
        page: '.page_load'
    }

javascript//全局公用部分
//文件位置 /public/js/init.js
$(function(){
    if (typeof pageAutoLoad != 'undefined') {
        $(window).scroll(function () {
            loadData();
        });
    }
});

var totalheight = 0;
function loadData() {
    totalheight = parseFloat($(window).height()) + parseFloat($(window).scrollTop());
    if ($(document).height() <= totalheight) {

        if (pageAutoLoad.page > pageAutoLoad.pageTotal) {
            return;
        }

        var nextPage = pageAutoLoad.page + 1;
        var nextUrl = pageAutoLoad.nextUrl.replace('PAGE', nextPage);

        $.ajax({
            url: nextUrl,
            type: 'GET',
            dataType: 'html',
            error: function () {
                $('.more-link').trigger('click');
            },
            success: function (html) {
                var htmlContent = $(html).find(pageAutoLoad.selector.content).html();
                var htmlPage = $(html).find(pageAutoLoad.selector.page).html();

                $(pageAutoLoad.selector.content).append(htmlContent);
                $(pageAutoLoad.selector.page).html(htmlPage);

                pageAutoLoad.page = nextPage;
            }
        });
    }
}

Answer 1

建议你还是用一个类来实现这个组件，参数设计的话可以参考以下

1. current_page //当前页
2. total_page //总页
3. fetch_url //加载地址（http://xxx.com/game/top-hot/p）
4. url_generate_method //组件真实加载地址的生成函数（传入fetch_url和current_page）
5. success_callback //加载成功后的回调
6. error_callback //失败的回调
   ...

不喜欢回调的方式可以基于jquery的自定义事件来解决。
写法大致就是$.fn.customName = function (options) {...}
然后调用的时候：$('selector').customName(options)

---

javascript// 组件定义
$.fn.pageAutoLoad = function (options) {
    var $element = $(this);
    var default_options = {
        current_page: 1,
        total_page: 2,
        fetch_url: undefined,
        url_generate_method: function (url, page) {
            return url + '/' + page;
        },
        success_callback: function (response, status) {},
        error_callback: function (error_msg) {}
    };

    options = $.extend({}, default_options, options);

    var loaddata = function () {
        $.ajax({
            url: options.url_generate_method(options.fetch_url, options.current_page),
            type: 'GET',
            dataType: 'html',
            error: function (jqxhr, status, error) {
                options.error_callback(error, status, jqxhr);
            },
            success: function (jqxhr, status, response) {
                // 更改当前的页数
                options.current_page += 1;
                options.success_callback(response, status, jqxhr);
            };
        });
    };

    $element.on('load_page', loaddata);
}

// 外部调用
$(window).scroll(function () {
    var options = {
        fetch_url: "http://xxx.com/game/top-hot/p",
        url_generate_method: function (url, page) {
            return url + '/' + page + '/';
        },
        success_callback: function (html) {
            //你的success
        }
    };
    $('.more-link').pageAutoLoad(options);

    //先判断是否满足加载条件，这里就不写了，以下是满足条件后的代码
    $('.more-link').trigger('load_page');
}

Answer 2

帮你把格式调了下：

//网址：http://xxx.com/game/top-hot/p/1/
//需要先引入jquery.min.js库
var pageAutoLoad = {
    page: 1,
    pageTotal: 2,
    nextUrl: "\/game\/top-hot\/p\/PAGE\/",
    selector: {
        content: '.list_game ul',
        page: '.page_load'
    }
};

//全局公用部分
//文件位置 /public/js/init.js
$(function(){
    var totalheight = 0;
    function loadData() {
        totalheight = parseFloat($(window).height()) + parseFloat($(window).scrollTop());
        if ($(document).height() <= totalheight) {
            if (pageAutoLoad.page > pageAutoLoad.pageTotal) {
                return;
            }
            var nextPage = pageAutoLoad.page + 1;
            var nextUrl = pageAutoLoad.nextUrl.replace('PAGE', nextPage);
            $.ajax({
                url: nextUrl,
                type: 'GET',
                dataType: 'html',
                error: function () {
                    $('.more-link').trigger('click');
                },
                success: function (html) {
                    var htmlContent = $(html).find(pageAutoLoad.selector.content).html();
                    var htmlPage = $(html).find(pageAutoLoad.selector.page).html();
                    $(pageAutoLoad.selector.content).append(htmlContent);
                    $(pageAutoLoad.selector.page).html(htmlPage);
                    pageAutoLoad.page = nextPage;
                }
            });
        }
    }
    if (typeof pageAutoLoad !== 'undefined') {
        $(window).scroll(function () {
            loadData();
        });
    }
});

Answer 3

重構如下：

主要是提取邏輯並抽象。

$.extend({
    InfiniteScroll: function(options) {
        var $window = $(window), $document = $(document);

        options = $.extend({
            onsuccess: function() {},
            onerror: function() {},
            onexhaust: function() {}
        }, options);

        function onscroll() {
            if ($document.height() <= $window.height() + $window.scrollTop() + 10)
                if (options.pageNum + 1 <= options.pageCount)
                    load();
                else
                    options.onexhaust(data);
        }
        function load() {
            var url = options.getUrl(options.pageNum + 1);

            $.ajax({
                url: url,
                type: 'GET',
                dataType: 'html',
                error: error,
                success: success
            });
        }
        function success(data) {
            options.onsuccess(data);
        }
        function error() {
            options.onerror();
        }

        return {
            onscroll: onscroll
        }
    }
});

$(function(){
    $(window).scroll($.InfiniteScroll({
        pageNum: 1,
        pageCount: 2,
        urlTemplate: '/game/top-hot/p/%PAGE%/',
        selector: {
            content: '.list_game ul',
            page: '.page_load'
        }, 
        getUrl: function(pageNum) {
            var url = this.urlTemplate.replace(/%PAGE%/g, pageNum);

            return url;
        },
        onsuccess: function(data) {
            var selector = this.selector,
                $data = $(data),
                content = $data.find(selector.content).html(),
                page = $data.find(selector.page).html();

            $(selector.content).append(content);
            $(selector.page).html(page);

            this.pageNum++;
        },
        onerror: function() {
            $('.more-link').trigger('click');
        }
    }).onscroll);
});