Method insertBefore

src/undom.js:56–61

(child, ref)

			return child;
		}
		insertBefore(child, ref) {
			child.remove();
			child.parentNode = this;
			!ref ? this.childNodes.push(child) : splice(this.childNodes, ref, child);
			return child;
		}
		replaceChild(child, ref) {
			if (ref.parentNode===this) {
				this.insertBefore(child, ref);