<pre id="output"></pre>

pre {
	padding: 0 1em;
	tab-size: 2;
	font: 80%/1.4 Consolas, Monaco, monospace;
}

let style = document.body.style;
let properties = Object.getOwnPropertyNames(style.hasOwnProperty("background")? style : style.__proto__);

properties = properties.filter(p => style[p] === "") // drop functions etc
	.map(prop => { // de-camelCase
		prop = prop.replace(/[A-Z]/g, function($0) { return '-' + $0.toLowerCase() });

		if (prop.startsWith("webkit-")) {
			prop = "-" + prop;
		}

		return prop;
	});

// Drop duplicates
properties = [...new Set(properties)];

output.textContent = JSON.stringify(properties, null, "\t");