Keyboard navigation on datatable

Hello. My English is not very good, that’s why minimum words and maximum code.
All code you can download on GitHub here.
In this article I want to suggest my implementation of keyboard navigation on datatable. This will be work only with primefaces version 4 or higher.
Suppose we have a table:

<p:dataTable id="dataTable" widgetVar="table" ...>
...
</p:dataTable> 

Lets wrap it with div which has attribute tabindex:

<div tabindex="1" id="table_div">
    <p:dataTable id="dataTable" widgetVar="table" ...>
        ...
    </p:dataTable>  
</div>

Tabindex gives us opportunity to get focus and bind keydown event on the table.
Now bind this events on div with jquery:

$("#table_div").keydown(function(event) {
    if (event.which === 38) {
        event.preventDefault();
        up();
    }

    if (event.which === 40) {
        event.preventDefault();
        down();
    }
});

and add functions for this events:

var down = function() {
    //If no rows selected, select first row
    if(PF('table').selection.length === 0){
        PF('table').selectRow(0);
        return;
    }
    //get index of selected row, if no row is selected return 0
    var index = PF('table').originRowIndex;
    //get amount of rows in the table
    var rows = PF('table').tbody[0].childElementCount;
    //increase row index
    index++;
    //if new index equals number of rows, set index to first row
    if (index === rows) {
        index = 0;
    }
    //deselect all selected rows
    PF('table').unselectAllRows();
    //select new row 
    PF('table').selectRow(index);
    //change originRowIndex value
    PF('table').originRowIndex = index;
};

var up = function() {
    //get amount of rows in the table
    var rows = PF('table').tbody[0].childElementCount;
    //get index of selected row, if no row is selected return 0
    var index = PF('table').originRowIndex;
    //if this is first row, set index to last row
    if (index === 0) {
        index = rows - 1;
    } else {
        index--;
    }
    //unselect all rows
    PF('table').unselectAllRows();
    //select previous row 
    PF('table').selectRow(index);
    //set index to current selected row
    PF('table').originRowIndex = index;
}

That’s all. Our table is ready. If you want to know how select element and send it to the server with enter button, download code from github. I don’t describe how to make navigation in the datatable with multiple selection, but I can do it if necessary.