IE 7- 을 지원하는 .querySelector(), .querySelectorAll() 대체 스크립트

polyfill-querySelectorAll.js

(function(document) {
	'use strict';

	if (!document.querySelectorAll) {
		document.querySelectorAll = function(selectors) {
			var style = document.createElement('style'),
				elements = [],
				element;
			document.documentElement.firstChild.appendChild(style);
			document._qsa = [];

			style.styleSheet.cssText = selectors + '{x-qsa:expression(document._qsa && document._qsa.push(this))}';
			window.scrollBy(0, 0);
			style.parentNode.removeChild(style);

			while (document._qsa.length) {
				element = document._qsa.shift();
				element.style.removeAttribute('x-qsa');
				elements.push(element);
			}
			document._qsa = null;
			return elements;
		};
	}

	if (!document.querySelector) {
		document.querySelector = function(selectors) {
			var elements = document.querySelectorAll(selectors);
			return (elements.length) ? elements[0] : null;
		};
	}

// https://github.com/inexorabletash/polyfill
})(document);