There's a lot you can do with this radar chart library. That doesn't mean you should use all of them all of the time. As these demos have shown, it is entirely possible for even the creator of the library - myself - to go overboard and create hideous-looking charts. Be judicious in your choice of options, and create the most compelling charts you can.

Before I list out the various choices and options, a few closing thoughts. Again, thanks to everyone who helped me with their time and opinions. Feel free to use this library as you see fit under the open-source MIT Licence terms. Put briefly, you can refer to it from my website where I host it, you can copy it along with the copyright message, you can use it for free either way. If you modify it for your own purposes, that's fine. If your modifications benefit others, submit a request to the github repository. I plan to add some more features when the time and mood strike me.

Instead of giving a JSON Schema for the configuration (which would be the right thing to do), let me dump a sample config file here to explain how to use it.

// To use the library, include the following script tags in your page.
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="radarChart.js"></script>

// To configure it, include a script tag like this.
<script>
// The config object is a JSON object.
var config =
{
	id: "radar",                     // id should match the div tag on the page.
	radius: 400,                     // required, the radius of the actual chart.
	title: "Countries of the World", // required
	legend: "right",                 // optional, values are right, left, top, bottom, none, default is right
	clockwise: false,                // optional, values are true/false, default false
	symmetric: false,                // optional, values are true/false, default false
	equidistant: false,              // optional, values are true/false, default false
	sections:                        // required, should contain at least one entry.
	[
		// id and name are required, colour is optional but strongly recommended, default is lightblue.
		{ id: "africa",     name: "Africa",     colour: "orange" },
		{ id: "americas",   name: "Americas",   colour: "lightgreen" },
		{ id: "asia",       name: "Asia",       colour: "#ff8888" },
		{ id: "europe",     name: "Europe",     colour: "#929244" },
		{ id: "oceania",    name: "Oceania",    colour: "lightblue" },
	],
	rings:                           // required, should contain at least one entry.
	[
		// id and name are required, colour is optional, default is a shade of grey.
		{ id: "rep",      name: "Republic" },
		{ id: "prov",     name: "Provisional" },
		{ id: "constmon", name: "Constitutional Monarchy" },
		{ id: "absmon",   name: "Absolute Monarchy" },
		{ id: "dict",     name: "Dictatorship", colour: "#bb22dd" },
	],
	entries:                         // required, should contain zero or more entries.
	[

// Simplest entry. section, ring and name are required. section and ring values should match the respective ids above.
{ section: 'americas', ring: 'rep', name: 'United States' },

// Most complex entry. Other than section, ring and name, everything else is optional and has sensible defaults.
{ section: 'asia', ring: 'rep', name: 'India', dr: '0.92822014024195', dt: '0.645', z: '11.057271246149', ds: '0.803366890307016', dc: '0.6', colour: 'lightblue' },
// dr is delta-radius, value should be [0,1], controls distance away from centre.
// dr is delta-angle, value should be [0,1], controls distance away from edge.
// z is z-value, value can be negative, controls height of bar.
// ds is delta-size, value should be [0,1], controls size of bar.
// dc is delta-colour, value should be [0,1], controls opacity of bar.
// colour is overriding colour, controls colour of bar.

	],
};
</script>

// To invoke the library with the config object above, add JavaScript:
<script>
	showRadar(config);
</script>

// To set up the radar, insert the div tag below into your page.
<div id="radar"></div>

To see any demo again, click on: Start, Demo 1, Demo 2, Demo 3, Demo 4, Demo 5, Demo 6.

Thanks for getting up to here!
    -- Anand