baseURI.ts

export const baseURI: string = ((): string => {
	if (document.baseURI) {
		return document.baseURI;
	}

	// Should be exactly one tag:
	//   https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base
	const base = document.getElementsByTagName('base');

	// Return location from BASE tag.
	if (base.length > 0) {
		return base[0].href;
	}

	// Else use implementation of documentURI:
	//   http://www.w3.org/TR/DOM-Level-3-Core/core.html#Node3-baseURI
	return document.URL;
})();