axe-core/lib/core/utils/node-sorter.js

Accessibility engine for automated Web UI testing

/**
 * Array#sort callback to sort nodes by DOM order
 * @private
 * @param  {Node} nodeA
 * @param  {Node} nodeB
 * @return {Integer}   @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Sort
 */
axe.utils.nodeSorter = function nodeSorter(nodeA, nodeB) {
	/*eslint no-bitwise: 0 */
	nodeA = nodeA.actualNode || nodeA;
	nodeB = nodeB.actualNode || nodeB;
	if (nodeA === nodeB) {
		return 0;
	}

	if (nodeA.compareDocumentPosition(nodeB) & 4) {
		return -1; // a before b
	} else {
		return 1; // b before a
	}
};