<html><head> <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/d3@7"></script></head><body><h3>D3 collection API</h3><script> var month = d3.map([{name: "jan"}, {name: "feb"}], function (d) { return d.name; }); console.log(month.get("jan")); // {"name": "jan"} console.log(month.get("apr")); // undefined console.log(month.has("feb")); // true var map = d3.map().set("fruit", "mango"); console.log(map.get("fruit")); // mango console.log(map.remove("fruit")); // remove key and return true. console.log(map.size()); // size is 0 because key removed. console.log(map.empty()); // true</script></body></html>