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一个分页插件的源码分析

2016-01-25 23:18 573 查看

/** * 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 * * 下面的写法我的理解是定义一个我任务的构造方法，或者方法，或者对象 * $.PaginationCalculator，这个$.PaginationCalculator对象中有两个参数 */ $.PaginationCalculator = function(maxentries, opts) { this.maxentries = maxentries; this.opts = opts; } /** * 对这个对象进行扩展$.PaginationCalculator，为它添加numPages方法，getInterval方法。 */ $.extend($.PaginationCalculator.prototype, { /** * Calculate the maximum number of pages * * @method * @returns {Number} * 编写一个获得页码的方法 * */ 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，下面的方式是定义一个对象 $.PaginationRenderers = {} /** * @class Default renderer for rendering pagination links * * 再次定义一个$.PaginationRenderers.defaultRenderer对象 */ $.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 class='current'>" + 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='pagination'></div>"); // 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 : "prev" })); } // 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) { $( "<span class='pagination-break'>" + 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) { $( "<span class='pagination-break'>" + 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 : "next" })); } $('a', fragment).click(eventHandler); return fragment; } }); // Extend jQuery，编写一个插件 $.fn.pagination = function(maxentries, opts) { // Initialize options with default values opts = $.extend( { items_per_page : 1, num_display_entries : 4, current_page : 0, num_edge_entries : 1, link_to : "#", prev_text : "<i></i>上一页", next_text : "下一页 <i></i>", ellipse_text : "...", prev_show_always : true, next_show_always : true, renderer : "defaultRenderer", show_if_single_page : false, load_first_page : false, callback : function() { return false; } }, opts || {}); var containers = this, renderer, links, current_page; // goto $(".page-btn").one("click", function() { var allPage = $(".allPage").text(); // console.log(allPage); var goPage = $(".page-go input").val() - 1; // 跳转页数 if (goPage > -1 && goPage < allPage) { opts.current_page = goPage; $("#Pagination").pagination(allPage, opts); } else { $("#Pagination").pagination(allPage); } // 清空用户跳转页数 $(".page-go input").val(""); }); /** * This is the event handling function for the pagination links. * * @param {int} * page_id The new page number */ function paginationClickHandler(evt) { var links, new_current_page = $(evt.target).data('page_id'), continuePropagation = selectPage(new_current_page); if (!continuePropagation) { evt.stopPropagation(); } return continuePropagation; } /** * This is a utility function for the internal event handlers. It sets * the new current page on the pagination container objects, generates a * new HTMl fragment for the pagination links and calls the callback * function. */ function selectPage(new_current_page) { // update the link display of a all containers containers.data('current_page', new_current_page); links = renderer.getLinks(new_current_page, paginationClickHandler); containers.empty(); links.appendTo(containers); // call the callback and propagate the event if it does not return // false var continuePropagation = opts.callback(new_current_page, containers); return continuePropagation; } // ----------------------------------- // Initialize containers // ----------------------------------- current_page = parseInt(opts.current_page); containers.data('current_page', current_page); // Create a sane value for maxentries and items_per_page maxentries = (!maxentries || maxentries < 0) ? 1 : maxentries; opts.items_per_page = (!opts.items_per_page || opts.items_per_page < 0) ? 1 : opts.items_per_page; if (!$.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; } }); 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(); if (np > 1 || opts.show_if_single_page) { links.appendTo(containers); } // call callback function if (opts.load_first_page) { opts.callback(current_page, containers); } } // End of $.fn.pagination block })(jQuery);

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