index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style>
.county {
fill: rgb(97, 183, 58);
stroke: #fff;
stroke-width: 2px;
}
.county.buffered {
fill: rgba(255, 255, 255, 0.3);
stroke: none;
}
</style>
</head>
<body>
<script src="//api.tiles.mapbox.com/mapbox.js/plugins/turf/v2.0.0/turf.min.js"></script>
<script src="//d3js.org/d3.v3.min.js" charset="utf-8"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/topojson/1.6.20/topojson.min.js"></script>
<script>
var width = 960,
height = 500;
var projection = d3.geo.conicConformal()
.rotate([90, 0])
.center([0.1995, 44.75])
.parallels([29.5, 45.5])
.scale(6000)
.translate([width/2, height/2])
.precision(0.1);
var path = d3.geo.path()
.projection(projection);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
d3.json("wi.json", function(error, wi) {
if (error) throw error;
wi = topojson.feature(wi, wi.objects.wi);
var wiBuffered = buffer(wi, -5, "miles");
svg.selectAll(".county").data(wi.features)
.enter().append("path")
.attr("class", "county")
.attr("d", path);
svg.selectAll(".county.buffered").data(wiBuffered.features)
.enter().append("path")
.attr("class", "county buffered")
.attr("d", path);
});
function buffer(featureCollection, distance, unit) {
var features = featureCollection.features
.map(function(feature) {
var buffered = null;
try { buffered = turf.buffer(feature, distance, unit); }
catch(e) { }
return buffered;
})
.filter(function(feature) { return feature !== null; });
return {
type: "FeatureCollection",
features: features,
properties: null
};
}
</script>
</body>
</html>