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@mbostock
Last active Feb 9, 2016
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Mouseenter
license: gpl-3.0

This example demonstrates mouseenter and mouseleave events. Mouseenter and mouseleave events are triggered only when the mouse enters or leaves the parent container; unlike mouseover and mouseout, they are not triggered when the mouse moves between descendant elements. This makes it easier to listen for when the mouse enters a group of elements and avoid unnecessary flickering.

For browsers that do not yet support mouseenter and mouseleave events, D3 provides a polyfill on top of the mouseover and mouseout events.

<!DOCTYPE html>
<meta charset="utf-8">
<style>
rect {
fill-opacity: .1;
stroke: #000;
shape-rendering: crispEdges;
}
rect:hover {
stroke: red;
}
text {
pointer-events: none;
text-anchor: middle;
font: 12px sans-serif;
text-shadow: 0 1px 0 #fff, 0 -1px 0 #fff, 1px 0 0 #fff, -1px 0 0 #fff;
}
text.mouseenter,
text.mouseleave {
fill: red;
font-weight: bold;
}
</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>
var width = 960,
height = 500;
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")")
.call(nest, 6, 30)
.on("mouseenter", flash("mouseenter", "-1em"))
.on("mouseover", flash("mouseover", "0"))
.on("mouseout", flash("mouseout", "1em"))
.on("mouseleave", flash("mouseleave", "2em"));
function flash(name, dy) {
return function() {
d3.select(this).append("text")
.attr("class", name)
.attr("transform", "translate(" + d3.mouse(this) + ")")
.attr("dy", dy)
.text(name)
.transition()
.duration(1500)
.style("opacity", 0)
.remove();
};
}
function nest(svg, levels, step) {
var g = svg.append("g");
g.append("rect")
.attr("x", -(levels + 1) * step)
.attr("y", -(levels + 1) * step)
.attr("width", (levels + 1) * step * 2)
.attr("height", (levels + 1) * step * 2);
if (levels > 0) g.call(nest, levels - 1, step);
}
</script>
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