Question

I’ve tried inspecting the DOM and so forth, and am not sure why ‘.tooltip’ is appended to the handler. It doesn’t effect anything if removed, and seemingly has no significant value:

    g.selectAll("circle")
        //
        //why is .tooltip appended here?
        //
        .on("mouseover.tooltip", function(d) {
        d3.select("text#" + d.line_id).remove();
        d3.select("#chart")
            .append("text")
            .text(d.late_percent + "%")
                .attr("x", time_scale(d.time) + 10)
                .attr("y", percent_scale(d.late_percent) - 10)
                .attr("id", d.line_id);
    });

Any clarification is much appreciated.

Answer 1

It’s a namespace

http://api.jquery.com/on/

http://docs.jquery.com/Namespaced_Events

“jQuery provides a concept called namespaced events: Simply add a
classname to your event when you declare it. You can then reference
that namespaced event both with unbind and trigger.”

$('.class').bind('click.namespace', function(){}); 
$('.class').trigger('click.namespace');
$('.class').unbind('click.namespace');