jQuery插件 dataTable Ajax分页功能实现

jQuery 的插件 dataTables 是一个优秀的表格插件，提供了针对表格的排序、浏览器分页、服务器分页、筛选、格式化等功能。需要可以到 dataTables 的网站 http://www.datatables.net/ 下载这个脚本库。

在网页开发过程中，我们可能会从后台读入数据建表。当数据过大时，可能导致建表时间过长，于是就需要实现Ajax分页功能，代码如下：

HTML：

<table id="example" class="display" width="100%" cellspacing="0">
        <thead>
            <tr>
                <th>First name</th>
                <th>Last name</th>
                <th>Position</th>
                <th>Office</th>
                <th>Start date</th>
                <th>Salary</th>
            </tr>
        </thead>

        <tfoot>
            <tr>
                <th>First name</th>
                <th>Last name</th>
                <th>Position</th>
                <th>Office</th>
                <th>Start date</th>
                <th>Salary</th>
            </tr>
        </tfoot>
    </table>

JS：

//
// Pipelining function for DataTables. To be used to the `ajax` option of DataTables
//
$.fn.dataTable.pipeline = function ( opts ) {
    // Configuration options
    var conf = $.extend( {
        pages: 5,     // number of pages to cache
        url: '',      // script url
        data: null,   // function or object with parameters to send to the server
                      // matching how `ajax.data` works in DataTables
        method: 'GET' // Ajax HTTP method
    }, opts );

    // Private variables for storing the cache
    var cacheLower = -1;
    var cacheUpper = null;
    var cacheLastRequest = null;
    var cacheLastJson = null;

    return function ( request, drawCallback, settings ) {
        var ajax          = false;
        var requestStart  = request.start;
        var drawStart     = request.start;
        var requestLength = request.length;
        var requestEnd    = requestStart + requestLength;

        if ( settings.clearCache ) {
            // API requested that the cache be cleared
            ajax = true;
            settings.clearCache = false;
        }
        else if ( cacheLower < 0 || requestStart < cacheLower || requestEnd > cacheUpper ) {
            // outside cached data - need to make a request
            ajax = true;
        }
        else if ( JSON.stringify( request.order )   !== JSON.stringify( cacheLastRequest.order ) ||
                  JSON.stringify( request.columns ) !== JSON.stringify( cacheLastRequest.columns ) ||
                  JSON.stringify( request.search )  !== JSON.stringify( cacheLastRequest.search )
        ) {
            // properties changed (ordering, columns, searching)
            ajax = true;
        }

        // Store the request for checking next time around
        cacheLastRequest = $.extend( true, {}, request );

        if ( ajax ) {
            // Need data from the server
            if ( requestStart < cacheLower ) {
                requestStart = requestStart - (requestLength*(conf.pages-1));

                if ( requestStart < 0 ) {
                    requestStart = 0;
                }
            }

            cacheLower = requestStart;
            cacheUpper = requestStart + (requestLength * conf.pages);

            request.start = requestStart;
            request.length = requestLength*conf.pages;

            // Provide the same `data` options as DataTables.
            if ( $.isFunction ( conf.data ) ) {
                // As a function it is executed with the data object as an arg
                // for manipulation. If an object is returned, it is used as the
                // data object to submit
                var d = conf.data( request );
                if ( d ) {
                    $.extend( request, d );
                }
            }
            else if ( $.isPlainObject( conf.data ) ) {
                // As an object, the data given extends the default
                $.extend( request, conf.data );
            }

            settings.jqXHR = $.ajax( {
                "type":     conf.method,
                "url":      conf.url,
                "data":     request,
                "dataType": "json",
                "cache":    false,
                "success":  function ( json ) {
                    cacheLastJson = $.extend(true, {}, json);

                    if ( cacheLower != drawStart ) {
                        json.data.splice( 0, drawStart-cacheLower );
                    }
                    json.data.splice( requestLength, json.data.length );

                    drawCallback( json );
                }
            } );
        }
        else {
            json = $.extend( true, {}, cacheLastJson );
            json.draw = request.draw; // Update the echo for each response
            json.data.splice( 0, requestStart-cacheLower );
            json.data.splice( requestLength, json.data.length );

            drawCallback(json);
        }
    }
};

// Register an API method that will empty the pipelined data, forcing an Ajax
// fetch on the next draw (i.e. `table.clearPipeline().draw()`)
$.fn.dataTable.Api.register( 'clearPipeline()', function () {
    return this.iterator( 'table', function ( settings ) {
        settings.clearCache = true;
    } );
} );

//
// DataTables initialisation
//
$(document).ready(function() {
    $('#example').dataTable( {
        "processing": true,
        "serverSide": true,
        "ajax": $.fn.dataTable.pipeline( {
            url: '',//后台处理URL，如：“scripts/server_processing.php”
            pages: 5 // 预读5页
        } )
    } );
} );

Response data：

{
  "draw": 2,
  "recordsTotal": 57,
  "recordsFiltered": 57,
  "data": [
    [
      "Tiger",
      "Nixon",
      "System Architect",
      "Edinburgh",
      "25th Apr 11",
      "$320,800"
    ],
    [
      "Timothy",
      "Mooney",
      "Office Manager",
      "London",
      "11th Dec 08",
      "$136,200"
    ],
    [
      "Unity",
      "Butler",
      "Marketing Designer",
      "San Francisco",
      "9th Dec 09",
      "$85,675"
    ],
    [
      "Vivian",
      "Harrell",
      "Financial Controller",
      "San Francisco",
      "14th Feb 09",
      "$452,500"
    ],
    [
      "Yuri",
      "Berry",
      "Chief Marketing Officer (CMO)",
      "New York",
      "25th Jun 09",
      "$675,000"
    ],
    [
      "Zenaida",
      "Frank",
      "Software Engineer",
      "New York",
      "4th Jan 10",
      "$125,250"
    ],
    [
      "Zorita",
      "Serrano",
      "Software Engineer",
      "San Francisco",
      "1st Jun 12",
      "$115,000"
    ]
  ]
}