Jquery.Pagination分页插件的学习

编程小白，文章中出现的谬误希望大神指点

工作接到一个任务，需要把现在pagination的样式修改成前端给的样式，当时心慌慌，幸好pagination的源码不太多，参考了一下网上的讲解代码，把学习过程中遇到的问题和对pagination的理解记录下来。

先看最终效果






直接上代码

/**
* This jQuery plugin displays pagination links inside the selected elements.
*
* This plugin needs at least jQuery 1.4.2
*
* @author Gabriel Birke (birke *at* d-scribe *dot* de)
* @version 2.2
* @param {int} maxentries Number of entries to paginate
* @param {Object} opts Several options (see README for documentation)
* @return {Object} jQuery Object
*/
(function($){
/**
* @class Class for calculating pagination values
*/
$.PaginationCalculator = function(maxentries, opts) {
this.maxentries = maxentries;
this.opts = opts;
}

$.extend($.PaginationCalculator.prototype, {
/**
* Calculate the maximum number of pages
* @method
* @returns {Number}
*/
numPages:function() {
return Math.ceil(this.maxentries/this.opts.items_per_page);
},
/**
* Calculate start and end point of pagination links depending on
* current_page and num_display_entries.
* @returns {Array}
*/
getInterval:function(current_page)  {
var ne_half = Math.floor(this.opts.num_display_entries/2);
var np = this.numPages();
var upper_limit = np - this.opts.num_display_entries;
var start = current_page > ne_half ? Math.max( Math.min(current_page - ne_half, upper_limit), 0 ) : 0;
var end = current_page > ne_half?Math.min(current_page+ne_half + (this.opts.num_display_entries % 2), np):Math.min(this.opts.num_display_entries, np);
return {start:start, end:end};
}
});

// Initialize jQuery object container for pagination renderers
$.PaginationRenderers = {}

/**
* @class Default renderer for rendering pagination links
*/
$.PaginationRenderers.defaultRenderer = function(maxentries, opts) {
this.maxentries = maxentries;
this.opts = opts;
this.pc = new $.PaginationCalculator(maxentries, opts);
}
$.extend($.PaginationRenderers.defaultRenderer.prototype, {
/**
* Helper function for generating a single link (or a span tag if it's the current page)
* @param {Number} page_id The page id for the new item
* @param {Number} current_page
* @param {Object} appendopts Options for the new item: text and classes
* @returns {jQuery} jQuery object containing the link
*/
createLink:function(page_id, current_page, appendopts){
var lnk, np = this.pc.numPages();
page_id = page_id<0?0:(page_id<np?page_id:np-1); // Normalize page id to sane value
appendopts = $.extend({text:page_id+1, classes:""}, appendopts||{});
if(page_id == current_page){
lnk = $("<a>" + appendopts.text + "</a>");
}
else
{
lnk = $("<a>" + appendopts.text + "</a>")
.attr('href', this.opts.link_to.replace(/__id__/,page_id));
}
if(appendopts.classes){ lnk.addClass(appendopts.classes); }
lnk.data('page_id', page_id);
return lnk;
},
// Generate a range of numeric links
appendRange:function(container, current_page, start, end, opts) {
var i;
for(i=start; i<end; i++) {
this.createLink(i, current_page, opts).appendTo(container);
}
},
getLinks:function(current_page, eventHandler) {
var begin, end,
interval = this.pc.getInterval(current_page),
np = this.pc.numPages(),
fragment = $("<div class='wy_1 y_z'></div>");

//创建首页链接
if(this.opts.first_text){
fragment.append(this.createLink(0, 0, {text:this.opts.first_text, classes:"wy_fy"}));
}

// Generate "Previous"-Link
if(this.opts.prev_text && (current_page > 0 || this.opts.prev_show_always)){
fragment.append(this.createLink(current_page-1, current_page, {text:this.opts.prev_text, classes:"wy_fy"}));
}

//创建中间页码显示
fragment.append("<span>" + (current_page+1) + "/"+np+"</span>");

// Generate starting points
// if (interval.start > 0 && this.opts.num_edge_entries > 0)
// {
// 	end = Math.min(this.opts.num_edge_entries, interval.start);
// 	this.appendRange(fragment, current_page, 0, end, {classes:'sp'});
// 	if(this.opts.num_edge_entries < interval.start && this.opts.ellipse_text)
// 	{
// 		jQuery("<span>"+this.opts.ellipse_text+"</span>").appendTo(fragment);
// 	}
// }
// // Generate interval links
// this.appendRange(fragment, current_page, interval.start, interval.end);
// // Generate ending points
// if (interval.end < np && this.opts.num_edge_entries > 0)
// {
// 	if(np-this.opts.num_edge_entries > interval.end && this.opts.ellipse_text)
// 	{
// 		jQuery("<span>"+this.opts.ellipse_text+"</span>").appendTo(fragment);
// 	}
// 	begin = Math.max(np-this.opts.num_edge_entries, interval.end);
// 	this.appendRange(fragment, current_page, begin, np, {classes:'ep'});

// }
// Generate "Next"-Link
if(this.opts.next_text && (current_page < np-1 || this.opts.next_show_always)){
fragment.append(this.createLink(current_page+1, current_page, {text:this.opts.next_text, classes:"wy_fy"}));
}

//创建尾页链接
if(this.opts.end_text){

fragment.append(this.createLink(np-1, np-1, {text:this.opts.end_text, classes:"wy_fy"}));
}
//创建共多少条
fragment.append("<span>共" + this.maxentries + "条</span>");
//创建每页多少条
fragment.append("<span>每页" + this.opts.items_per_page +"条</span>");
//创建跳转

fragment.append("<span>跳转到<input type='text' value='' placeholder='' class='f_input'/>页</span>");
if(this.opts.go_text){
fragment.append(this.createLink(current_page, current_page, {text:this.opts.go_text, classes:"go"}));
}
$('a', fragment).click(eventHandler);
return fragment;
}
});

// Extend jQuery
$.fn.pagination = function(maxentries, opts){

// Initialize options with default values
opts = jQuery.extend({
items_per_page:10, //每页最多显示的记录数
num_display_entries:11,//可见页码数量
current_page:0,//当前页
num_edge_entries:1,//如果设置为1，显示首页与尾页，然而并没有什么效果，不知道为什么
link_to:"#",//链接
prev_text:"Prev",
next_text:"Next",
ellipse_text:"...",//当页码之间的数组相差很远时，显示的内容
prev_show_always:true,
next_show_always:true,
renderer:"defaultRenderer",
load_first_page:false,//插件初始化时被执行
callback:function(){return false;}
},opts||{});

var containers = this,
renderer, links, current_page;

/**
* This is the event handling function for the pagination links.
* @param {int} page_id The new page number
*/
function paginationClickHandler(evt){

var links;
var	new_current_page = $(evt.target).data('page_id');

<span style="white-space:pre">			</span>//这里就是点击跳转的代码，核心是获取到input框内用户输入的页数，进行简单判断后，将值作为当前页

<span style="white-space:pre">			</span>//传递给selectPage方法，让它重新调用本页方法重新生成链接

if($(evt.target).attr('class')=='go' && $('input[class=f_input]').val() !='' && !isNaN($('input[class=f_input]').val())){
new_current_page = $('input[class=f_input]').val() - 1;
new_current_page = Math.min(np-1,Math.max(0,new_current_page));
}
var	continuePropagation = selectPage(new_current_page);
if (!continuePropagation) {
evt.stopPropagation();
}
return continuePropagation;
}

/**
* This is a utility function for the internal event handlers.
* It sets the new current page on the pagination container objects,
* generates a new HTMl fragment for the pagination links and calls
* the callback function.
*/
function selectPage(new_current_page) {
// update the link display of a all containers
containers.data('current_page', new_current_page);
links = renderer.getLinks(new_current_page, paginationClickHandler);
containers.empty();
links.appendTo(containers);
// call the callback and propagate the event if it does not return false
var continuePropagation = opts.callback(new_current_page, containers);
return continuePropagation;
}

// -----------------------------------
// Initialize containers
// -----------------------------------
current_page = opts.current_page;
containers.data('current_page', current_page);
// Create a sane value for maxentries and items_per_page
maxentries = (!maxentries || maxentries < 0)?1:maxentries;
opts.items_per_page = (!opts.items_per_page || opts.items_per_page < 0)?1:opts.items_per_page;

if(!$.PaginationRenderers[opts.renderer])
{
throw new ReferenceError("Pagination renderer '" + opts.renderer + "' was not found in jQuery.PaginationRenderers object.");
}
renderer = new $.PaginationRenderers[opts.renderer](maxentries, opts);

// Attach control events to the DOM elements
var pc = new $.PaginationCalculator(maxentries, opts);
var np = pc.numPages();
containers.bind('setPage', {numPages:np}, function(evt, page_id) {
if(page_id >= 0 && page_id < evt.data.numPages) {
selectPage(page_id); return false;
}
});

</pre><pre name="code" class="javascript"><span style="white-space:pre">		</span>这里的PrevPage、nextPage我不知道哪里来的，希望有人讲解，
containers.bind('prevPage', function(evt){
var current_page = $(this).data('current_page');
if (current_page > 0) {
selectPage(current_page - 1);
}
return false;
});
containers.bind('nextPage', {numPages:np}, function(evt){
var current_page = $(this).data('current_page');
if(current_page < evt.data.numPages - 1) {
selectPage(current_page + 1);
}
return false;
});

// When all initialisation is done, draw the links
links = renderer.getLinks(current_page, paginationClickHandler);
containers.empty();
links.appendTo(containers);
// call callback function
if(opts.load_first_page) {
opts.callback(current_page, containers);
}
} // End of $.fn.pagination block

})(jQuery);

插件首先调用Initialize containers下的方法，构造链接，完成后将生成的内容放到指定ID的容器内，上配置：

callback: pageselectCallback,//PageCallback() 为翻页调用次函数。
items_per_page:parseInt($("#pages").attr('data-epage')), //每页最多显示的记录数
num_display_entries:0,//可见页码数量
current_page: parseInt($("#pages").attr('data-page')),
num_edge_entries:0,//如果设置为1，显示首页与尾页
//link_to:"#",//链接
prev_text:"上一页",
next_text:"下一页",
first_text:"首页",
end_text:"尾页",
go_text:"GO",
ellipse_text:"",//当页码之间的数组相差很远时，显示的内容
prev_show_always:true,
next_show_always:true,
//renderer:"defaultRenderer",
load_first_page:false,//插件初始化时被执行

可以添加自定义参数，比如我添加的first_text、end_text、go_text,这里在构造按钮的时候使用，在这里

if(this.opts.first_text){
fragment.append(this.createLink(0, 0, {text:this.opts.first_text, classes:"wy_fy"}));
}

其中的0,0就代表首页，第一个0是页码的起始参数，第二个0是页码的结束参数，那尾页的参数是什么呢？ 是Pagination的一个变量np,调用创建链接的函数，其中text就是要显示的内容，first_text就是我们在初始化参数里面自己定义的，classes就是当前连接的样式，可以修改成自己的。