5.3 tooltip

<!DOCTYPE html>
<meta charset="utf-8">
<html>
<head>

<link href="https://fonts.googleapis.com/css2?family=Montserrat+Alternates:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;0,800;0,900;1,100;1,200;1,300;1,400;1,500;1,600;1,700;1,800;1,900&family=Montserrat:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;0,800;0,900;1,100;1,200;1,300;1,400;1,500;1,600;1,700;1,800;1,900&family=Roboto:ital,wght@0,100;0,300;1,100;1,300&display=swap" rel="stylesheet">

<script src="https://d3js.org/d3.v3.min.js"></script>

<p id="h1">TOOLTIP</p>
<div id="link">by
<a href="https://slides.com/sandravizmad">SANDRA</a></div>

<style>

/*Defining text stylings*/

#h1 {
  font-size:30px;
  margin:30px 0px 0px 20px;
  color:#f5fa91;
  font-family: 'Montserrat Alternates', sans-serif;
  font-weight:300;
}

#link {
	font-family:'Montserrat Alternates', sans-serif;
  font-weight:200;
  font-size:10px;
	margin:5px 0px 0px 22px;
  color:white;
}

a:link, a:visited, a:active {
	text-decoration: none;
  color:white;
  border-bottom:1.5px dotted white;
}

body {
  background-color:#011227;
}

/*Defining chart stylings*/

circle {
	fill:#85f6fa;
  opacity:0.5;
}

.tt {
  font-family:'Montserrat Alternates', sans-serif;
  font-weight:900;
  font-size:36px;
  color:#8ff798;
}

</style>
</head>

//Margin conventions
var m = {top:100, right:50, bottom:50, left:40}
    w = 700 - m.left - m.right,
    h = 700 - m.top - m.bottom;

//Container
var svg = d3.select("body")
    .append("svg")
    .attr("width", w + m.left + m.right)
    .attr("height", h + m.top + m.bottom)
    .append("g")
		.attr("transform", `translate(${m.left}, ${m.top})`);

var tt = d3.select("body")
    .append("div")
		.attr("class", "tt")
    .style("position", "absolute")
    .style("visibility", "hidden")
    .text("YUHU");

//Adding the circle
d3.select("svg")
  .append("circle")
  .attr("class", "circle")
  .attr("r", 200)
  .attr("cx", 300)
  .attr("cy", 300)
  .on("mouseover",() => tt.style("visibility", "visible"))
  .on("mousemove",() => tt.style("top", (event.pageY + 10) + "px")
      									  .style("left", (event.pageX + 10) + "px"))
  .on("mouseout",() =>  tt.style("visibility", "hidden"));

</script>
</body>
</html>

https://d3js.org/d3.v3.min.js