javascript - 这个事件处理程序在做什么？

Question

我尝试过检查 DOM 等，但不确定为什么将“.tooltip”附加到处理程序中。如果删除它不会产生任何影响，并且似乎没有重大值(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);
    });

非常感谢任何澄清。

Answer 1

这是一个命名空间

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');