Use a field value to update Group Title before submit

Is there a way to use a field value from a text field within a group to update the Group Title?

I am hoping to update it before the post is submitted. More than likely on field change/blur.

Something like:

array (
    'group_title' => {my_text_field.value},
    'id' => 'fb_week_games',
    'type' => 'group',
    'fields' => array(
        array(
            'name' => 'My text',
            'id' => 'my_text_field',
            'type' => 'text',
        ),
    ),
),