javascript svg onmouseover效果

Question

how do I have popups boxes when moving the mouse over the circle?

I have been trying hours to figure this out. Is it possible to only work on the code in javascript file here without changing anything in the html file?

javascript:

 svg.selectAll("circle")
 .data(sales)
 .enter()

 .....//other circle attributes

 .onmouseover = function(d,i){
    alert("haha");
}

Even the simple alert function didn't work. Nothing showed up when I moved over the circle. this is my first day learning data visualization please help out a newbie thanks!

Answer 1

Bind event handler by using selection. on

 svg.selectAll("circle")
 .data(sales)
 .enter()

 .....//other circle attributes

 .on('mouseover', function(){
     d3.select(this).style('fill', 'red');
  })

JSFiddle Demo: http://jsfiddle.net/sj8gLopz/