Colon-delimited tree setting thingy in JavaScript

setter.js

let data = {};

const setter = (o, p, v) => {
	if (typeof p === "string") {
		return setter(o, p.split(/\s*:\s*/), v);
	}
	if (p.length === 1) {
		o[p[0]] = v;
		return o;
	}
	const k = p.shift();
	o[k] = setter(o[k] ? o[k] : {}, p, v);
	return o;
};

setter(data, "name:first", "Fred");
setter(data, "name:last", "Flintstone");
setter(data, "phone:personal:mobile", "555-1212");