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@mbostock
Created January 26, 2017 21:24
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Border Mesh
license: gpl-3.0
height: 600
border: no

This example uses topojson.mesh to highlight California’s borders with its three neighboring states.

<!DOCTYPE html>
<svg width="960" height="600" fill="none" stroke-linejoin="round" stroke-linecap="round"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/topojson.v2.min.js"></script>
<script>
var svg = d3.select("svg");
var path = d3.geoPath();
d3.json("https://d3js.org/us-10m.v1.json", function(error, us) {
if (error) throw error;
svg.append("g")
.attr("fill", "#000")
.selectAll("path")
.data(topojson.feature(us, us.objects.states).features)
.enter().append("path")
.attr("d", path)
.append("title")
.text(function(d) { return d.id; });
svg.append("path")
.attr("stroke", "#fff")
.attr("stroke-width", 0.5)
.attr("d", path(topojson.mesh(us, us.objects.states, function(a, b) { return a !== b; })));
// California-Nevada border
svg.append("path")
.attr("stroke", "cyan")
.attr("stroke-width", 2.5)
.attr("d", path(topojson.mesh(us, us.objects.states, border("06", "32"))));
// California-Arizona border
svg.append("path")
.attr("stroke", "magenta")
.attr("stroke-width", 2.5)
.attr("d", path(topojson.mesh(us, us.objects.states, border("06", "04"))));
// California-Oregon border
svg.append("path")
.attr("stroke", "yellow")
.attr("stroke-width", 2.5)
.attr("d", path(topojson.mesh(us, us.objects.states, border("06", "41"))));
});
function border(id0, id1) {
return function(a, b) {
return a.id === id0 && b.id === id1
|| a.id === id1 && b.id === id0;
};
}
</script>
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