tooltip = {
chart
const tooltip = d3.select("body").append("div")
.attr("class", "svg-tooltip")
.style("position", "absolute")
.style("visibility", "hidden")
.text("I'm a circle!");
d3.select("#circle")
.on("mouseover", function(){
return tooltip.style("visibility", "visible");
})
.on("mousemove", function(){
return tooltip.style("top", (d3.event.pageY-10)+"px").style("left",(d3.event.pageX+10)+"px");
})
.on("mouseout", function(){
return tooltip.style("visibility", "hidden");
});
}