toggle.js

;(function(document, window, undefined) {

	'use strict';

	if (!document.addEventListener || !('classList' in document.createElement('span'))) { // classList = IE11
		return;
	}

	function widget_toggle(e) {

		var widget_ref = document.getElementById(this.getAttribute('aria-controls'));

		if (widget_ref.getAttribute('aria-hidden') == 'true') {

			this.setAttribute('aria-expanded', 'true');
			this.textContent = this.getAttribute('data-toggle-hidden');

			widget_ref.setAttribute('aria-hidden', 'false');
			widget_ref.focus();

		} else {

			this.setAttribute('aria-expanded', 'false');
			this.textContent = this.getAttribute('data-toggle-shown');

			widget_ref.setAttribute('aria-hidden', 'true');

		}

		e.preventDefault();

	}

	function init() {

		var links = document.querySelectorAll('a[data-toggle-hidden]'),
			widget_ref_id,
			widget_ref;

		for (var k = (links.length - 1); k >= 0; k--) {

			widget_ref_id = links[k].getAttribute('href').substr(1);
			widget_ref = document.getElementById(widget_ref_id);

			if (widget_ref) {

				widget_ref.setAttribute('aria-hidden', 'true');
				widget_ref.setAttribute('tabindex', '-1');
				widget_ref.style.outline = 'none';

				links[k].setAttribute('data-toggle-shown', links[k].textContent);
				links[k].setAttribute('role', 'button');
				links[k].setAttribute('aria-expanded', 'false');
				links[k].setAttribute('aria-controls', widget_ref_id);
				links[k].addEventListener('click', widget_toggle);

			}

		}

	}

	if (document.readyState !== 'loading') {
		window.setTimeout(init); // Handle asynchronously
	} else {
		document.addEventListener('DOMContentLoaded', init);
	}

})(document, window);