pageElement TOC checker

pageElement.innerHTML = pageElement.innerHTML.replace(/<h([\d]).*>([^<]+)<\/h([\d])>/gi, (str, openLevel, titleText, closeLevel) => {
		if (openLevel != closeLevel)
			return str;

		if (openLevel > level)
			toc += (new Array(openLevel - level + 1)).join('<ul>');
		else if (openLevel < level)
			toc += (new Array(level - openLevel + 1)).join('</li></ul>');
		else
			toc += (new Array(level+ 1)).join('</li>');

		level = parseInt(openLevel);

		var anchor = titleText.toLowerCase().replace(/ /g, "_");
		toc += '<li><a href="#' + anchor + '">' + titleText + '</a>';

		return str;
	});