Question

Using this function. But it adds row_selected class to all rows. How can I add it, only to parent row?

$('.checkbox').click( function() {
    if ( $("#list tr").hasClass('row_selected') )
        $("#list tr").removeClass('row_selected');
    else
        $("#list tr").addClass('row_selected');
} );

Answer 1

You can use the .closest() method to find the nearest parent (or grandparent/ancestor) element matching a particular selector. So try this:

$('.checkbox').click( function() {
   $(this).closest("tr").toggleClass("row_selected");
});

Note that the .toggleClass() method takes care of your if/else for you, but if you really want to code it manually:

$('.checkbox').click( function() {
    // store the reference to the containing tr in a variable instead of
    // reselecting it
    var $tr = $(this).closest("tr");
    if ($tr.hasClass('row_selected') )
        $tr.removeClass('row_selected');
    else
        $tr.addClass('row_selected');
});

Note that either way, in a jQuery event handler this is the element the event was triggered on, so you can manipulate it or find its parents/siblings/whatever by getting a jQuery object with $(this).