我想创建一个包含php变量的文件.json？

Finally i made a file end-named with the php extension file.json.php, and manage it like a php normal file but adding an echo with the function json_encode().

This is a extract of how i made the file.

  //only making to arrays an array (in this case for datatables dynamic columns on the fly)

    $columns[] = array("data" => "id", "name"=>"Id");
    $columns[] = array("data" => "number", "name"=>"numeroItem");
    $columns[] = array("data" => "item", "name"=>"Item");

    $a = array();
    $a['id'] = $row[$k]['id'];
    $a['number'] = $row[$k]['number'];
    $a['item']= $row[$k]['Item'];


    $data[] = $a;

    $json_for_datatable = array("columns" => $columns, "data" => $data);

    echo json_encode($json_for_datatable);

For configuration or considerations is necessary to receive de responseText with the function JSON.parse(), ¡This is important!

data = JSON.parse(jqxhr.responseText);

For considering in the ajax call

var data,
            tableName = '#exampleTablaDinamica'+$(this).attr("data-id"),
            columns, str,
            jqxhr = $.ajax('../files/data/data.json.php?idPartida='+$(this).attr("data-idpartida")+'&meses='+ selected +'&idPresupuesto='+$('#idPresupuesto').val())
                    .done(function () {
                        data = JSON.parse(jqxhr.responseText);
            // Iterate each column and print table headers for Datatables
            $(tableName + " thead").html("<tr></tr>");

            $.each(data.columns, function (k, colObj) {
                str = '<th>' + colObj.name + '</th>';
                $(str).appendTo(tableName+'>thead>tr');
            });
            // Add some Render transformations to Columns
            // Not a good practice to add any of this in API/ Json side



            data.columns[0].render = function (data, type, row) {
                return data;
            }
            data.columns[1].render = function (data, type, row) {
                return data;
            }
            data.columns[2].render = function (data, type, row) {
                return "<a href='a.php'>" + data + "</a>";
            }

            // Debug?
            console.log(data.columns[0]);

            if ( $.fn.DataTable.isDataTable(tableName) ) {
              $(tableName).DataTable().destroy();

            }


            table = $(tableName).dataTable({
                "data": data.data,
                "columns": data.columns,
                "responsive":true,
                "fnInitComplete": function () {
                    // Event handler to be fired when rendering is complete (Turn off Loading gif for example)
                    console.log('Datatable rendering complete');
                }
            });

        })
        .fail(function (jqXHR, exception) {
                        var msg = '';
                        if (jqXHR.status === 0) {
                            msg = 'Not connect.
 Verify Network.';
                        } else if (jqXHR.status == 404) {
                            msg = 'Requested page not found. [404]';
                        } else if (jqXHR.status == 500) {
                            msg = 'Internal Server Error [500].';
                        } else if (exception === 'parsererror') {
                            msg = 'Requested JSON parse failed.';
                        } else if (exception === 'timeout') {
                            msg = 'Time out error.';
                        } else if (exception === 'abort') {
                            msg = 'Ajax request aborted.';
                        } else {
                            msg = 'Uncaught Error.
' + jqXHR.responseText;
                        }
            console.log(msg);
        });

And finally this is the generated JSON content.

{
"columns": [{
    "data": "id",
    "name": "Id"
}, {
    "data": "number",
    "name": "number"
}, {
    "data": "item",
    "name": "Item"
}, {
    "data": "10 2018",
    "name": "10 2018"
}, {
    "data": "11 2018",
    "name": "11 2018"
}, {
    "data": "total",
    "name": "total"
}],
"data": [{
    "id": "1",
    "number": "1.1",
    "item": "loremipsum  loremipsum  loremipsum  loremipsum  ",
    "10 2018": "0",
    "11 2018": "0",
    "total": "20.741"
}]
}