​

var table = new DataTable('#example', {

   layout: {

        topStart: 

            'buttons'

    },

  "footerCallback": function(row, data, start, end, display) {

                var api = this.api();

                api.columns('.sum', {

                    page: 'current'

                    }).every(function() {

                    var sum = 0;

                    var td = this.nodes();

                    $(td).each(function(index, value) {

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                          var valore = parseFloat($(this).text());

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                          sum = sum + valore; 

                    });

                    $(this.footer()).html(sum.toFixed(2)); 

                });

    },

    buttons: [

                {

                    extend: 'colvis',

                    text: 'Show columns ',

                    columns: ':not(.noVis)'

                },

                {

                    extend: 'collection',

                    text: 'Export',

                    buttons: [

                        {

                            extend: 'excelHtml5',

                            footer: true,

                            text: 'Excel',

                            exportOptions: {

                                columns: [ ':not(.noVis):visible' ],

                                format: {

                                    body: function(data, row, column, node) {

                                        if (typeof data === 'string' || data instanceof String) {

                                            data = $('<div>' + data + '</div>'); // rimuovi i noExport tramite jquery

                                            data.find(".noExport").remove();

                                            data = data.html();

                                            data = data.replace( /<\/li>/ig, "\n"); //convert <li> tag to newline 

                                            data = data.replace( /<li\b[^>]*>/ig, "- ");

                                            data = data.replace( /<\/p>/ig, "\n"); //convert <p> tag to newline 

                                            data = data.replace( /<p\b[^>]*>/ig, "");

                                            data = data.replace( /<br\s*\/?>/ig, "\n"); //convert <br> tag to newline 

                                            data = data.replace(/[ \t]+/g, ' '); //remove unwanted tabs

                                            data = data.split(/\r?\n/); //split by newline

                                            data = data.map(s => s.trim()); // trim all string in array

                                            data = data.filter(item => item); //remove empty array string

                                            data = data.join('\n'); //recreate clean string

                                        }

                                        data = $('<p>' + data + '</p>').text(); // dopo le varie manipolazioni, posso eliminare l'html

                                        data = data.trim(); //elimino eventuali spaziature inizio/fine residue

                                        return data;

                                    },

                                    footer: function(data, row, column, node) {

                                        if (typeof data === 'string' || data instanceof String) {

                                            data = $('<div>' + data + '</div>'); // rimuovi i noExport tramite jquery

                                            data.find(".noExport").remove();

                                            data = data.html();

                                            data = data.replace( /<\/li>/ig, "\n"); //convert <li> tag to newline 

                                            data = data.replace( /<li\b[^>]*>/ig, "- ");

                                            data = data.replace( /<\/p>/ig, "\n"); //convert <p> tag to newline 

                                            data = data.replace( /<p\b[^>]*>/ig, "");

                                            data = data.replace( /<br\s*\/?>/ig, "\n"); //convert <br> tag to newline 

                                            data = data.replace(/[ \t]+/g, ' '); //remove unwanted tabs

                                            data = data.split(/\r?\n/); //split by newline

                                            data = data.map(s => s.trim()); // trim all string in array

                                            data = data.filter(item => item); //remove empty array string

                                            data = data.join('\n'); //recreate clean string

                                        }

                                        data = $('<p>' + data + '</p>').text(); // dopo le varie manipolazioni, posso eliminare l'html

                                        data = data.trim(); //elimino eventuali spaziature inizio/fine residue

                                        return data;

                                    }

                                }

                            },

                            createEmptyCells: true, // <-- importante per manipolare gli stili delle celle vuote

                            customize: function( xlsx ) {

                                var styles = $('cellXfs', xlsx.xl['styles.xml']);

                                // Append vertical="top" + wrap text style

                                styles.append('<xf numFmtId="0" fontId="0" fillId="0" borderId="0" xfId="0" applyFont="1" applyFill="1" applyBorder="1" applyAlignment="1">' + '<alignment vertical="top" wrapText="1" />' + '</xf>');

                                var sheet = xlsx.xl.worksheets['sheet1.xml'];

                                var oxf = $('xf', xlsx.xl['styles.xml']);

                                var rows = $('row', sheet);

                                /*

                                    oxf starts with a default format of:

                                    <xf numFmtId="0" fontId="0" fillId="0" borderId="0"/>

                                    DataTables creates it's styles here:

                                    https://github.com/DataTables/Buttons/blob/c25ea69f9241501b36193afffb91196928aab18f/js/buttons.html5.js#L645

                                    oxf.length = oxf default (1) + datatables styles + additional styles appended above

                                    For example 1 + 68 + 1 = 70

                                    To choose the appended style above 1 must be subtracted for the default 

                                    and 1 subtracted for 0 index, thus styleIndex - 2 to access the last appended style.

                                */

                                var styleIndex = oxf.length;

                                var vertTopWrapIndex = styleIndex - 2;

                                // corpo

                                $('row c', sheet).attr( 's', vertTopWrapIndex );    // set cell style: vertical top + wrapped text

                                //header (2 righe) in bold con sfondo gray e bordo sottile: lista codici: https://datatables.net/reference/button/excelHtml5

                                $('row:eq(0) c', sheet).attr( 's', '32' );

                                $('row:eq(1) c', sheet).attr( 's', '32' );

                                $('row:eq('+(rows.length-1)+') c', sheet).attr( 's', '32' ); //footer

                            }

                        },

                        {

                            extend: 'pdfHtml5',

                            footer: true,

                            orientation: 'landscape',

                            pageSize : 'A4',

                            text: 'PDF',

                            customize: function(doc) {

                                var rows = doc.content[1].table.body.length;  // ALLINEA A DX GLI IMPORTi

                                for (var i = 0; i < rows; i++) {

                                    var colonne = doc.content[1].table.body[i].length;

                                    for (var k = 0; k < colonne; k++) {

                                        if (

                                          $(table.row(i).column(k).nodes()).hasClass("valuta") ||

                                          $(table.row(i).column(k).nodes()).hasClass("age")

                                        ) {

                                            doc.content[1].table.body[i][k].alignment = 'right';

                                        }

                                    }

                                }

                                doc['footer']=(function(page, pages) {  //  CONTA PAGINE

                                    return {

                                        columns: [

                                            '', //LEFT

                                            {

                                                alignment: 'right',

                                                text: [

                                                    'Pag. ', 

                                                    { text: page.toString() },

                                                    ' di ',

                                                    { text: pages.toString() }

                                                ]

                                            }

                                        ],

                                        margin: [10, 0]

                                    }

                                });

                            },

                            exportOptions: {

                                columns: [ ':not(.noVis):visible' ],

                                format: {

                                    body: function ( data, row, column, node ) {

                                        if (typeof data === 'string' || data instanceof String) {

                                            data = $('<div>' + data + '</div>'); // rimuovi i noExport tramite jquery

                                            data.find(".noExport").remove();

                                            data = data.html();

                                            data = data.replace( /<\/li>/ig, "\n"); //convert <li> tag to newline 

                                            data = data.replace( /<li\b[^>]*>/ig, "- ");

                                            data = data.replace( /<\/p>/ig, "\n"); //convert <p> tag to newline 

                                            data = data.replace( /<p\b[^>]*>/ig, "");

                                            data = data.replace( /<br\s*\/?>/ig, "\n"); //convert <br> tag to newline 

                                            data = data.replace(/[ \t]+/g, ' '); //remove unwanted tabs

                                            data = data.split(/\r?\n/); //split by newline

                                            data = data.map(s => s.trim()); // trim all string in array

                                            data = data.filter(item => item); //remove empty array string

                                            data = data.join('\n'); //recreate clean string

                                        }

                                        data = $('<p>' + data + '</p>').text();

                                        data = data.trim(); //elimino eventuali spaziature inizio/fine residue

                                        return data;

                                    },

                                    footer: function ( data, column, node ) {

                                        if (typeof data === 'string' || data instanceof String) {

                                            data = $('<div>' + data + '</div>'); // rimuovi i noExport tramite jquery

                                            data.find(".noExport").remove();

                                            data = data.html();

                                            data = data.replace( /<\/li>/ig, "\n"); //convert <li> tag to newline 

                                            data = data.replace( /<li\b[^>]*>/ig, "- ");

                                            data = data.replace( /<\/p>/ig, "\n"); //convert <p> tag to newline 

                                            data = data.replace( /<p\b[^>]*>/ig, "");

                                            data = data.replace( /<br\s*\/?>/ig, "\n"); //convert <br> tag to newline 

                                            data = data.replace(/[ \t]+/g, ' '); //remove unwanted tabs

                                            data = data.split(/\r?\n/); //split by newline

                                            data = data.map(s => s.trim()); // trim all string in array

                                            data = data.filter(item => item); //remove empty array string

                                            data = data.join('\n'); //recreate clean string

                                        }

                                        data = $('<p>' + data + '</p>').text();

                                        data = data.trim(); //elimino eventuali spaziature inizio/fine residue

                                        return data;

                                    }

                                }

                            }

                        }

                    ]

                },

                'pageLength'

            ] 

});

​

​