axe-core/lib/commons/dom/is-in-text-block.js

Accessibility engine for automated Web UI testing

/* global axe, dom, window */
function walkDomNode(node, functor) {
	if (functor(node.actualNode) !== false) {
		node.children.forEach(child => walkDomNode(child, functor));
	}
}

var blockLike = ['block', 'list-item', 'table', 'flex', 'grid', 'inline-block'];
function isBlock(elm) {
	var display = window.getComputedStyle(elm).getPropertyValue('display');
	return (blockLike.includes(display) || display.substr(0, 6) === 'table-');
}

function getBlockParent (node) {
	// Find the closest parent
	let parentBlock = dom.getComposedParent(node);
	while (parentBlock && !isBlock(parentBlock)) {
		parentBlock = dom.getComposedParent(parentBlock);
	}
	return axe.utils.getNodeFromTree(axe._tree[0], parentBlock);
}

/**
 * Determines if an element is within a text block
 * @param  {Element} node [description]
 * @return {Boolean}      [description]
 */
dom.isInTextBlock = function isInTextBlock(node) {
	/* eslint complexity: ["error",17]*/
	if (isBlock(node)) {
		// Ignore if the link is a block
		return false;
	}

	// Find all the text part of the parent block not in a link, and all the text in a link
	const virtualParent = getBlockParent(node);
	let parentText = '';
	let linkText = '';
	let inBrBlock = 0;

	// We want to ignore hidden text, and if br / hr is used, only use the section of the parent
	// that has the link we're looking at
	walkDomNode(virtualParent, function (currNode) {
		// We're already passed it, skip everything else
		if (inBrBlock === 2) {
			return false;
		}

		if (currNode.nodeType === 3) {
			// Add the text to the parent
			parentText += currNode.nodeValue;
		}
		// Ignore any node that's not an element (or text as above)
		if (currNode.nodeType !== 1) {
			return;
		}

		var nodeName = (currNode.nodeName || '').toUpperCase();
		// BR and HR elements break the line
		if (['BR', 'HR'].includes(nodeName)) {
			if (inBrBlock === 0) {
				parentText = '';
				linkText = '';
			} else {
				inBrBlock = 2;
			}

		// Don't walk nodes with content not displayed on screen.
		} else if (currNode.style.display === 'none' ||
				currNode.style.overflow === 'hidden' ||
				!['', null, 'none'].includes(currNode.style.float) ||
				!['', null, 'relative'].includes(currNode.style.position)) {
			return false;

		// Don't walk links, we're only interested in what's not in them.
		} else if ((nodeName === 'A' && currNode.href) ||
				(currNode.getAttribute('role') || '').toLowerCase() === 'link') {
			if (currNode === node) {
				inBrBlock = 1;
			}
			// Grab all the text from this element, but don't walk down it's children
			linkText += currNode.textContent;
			return false;
		}
	});

	parentText = axe.commons.text.sanitize(parentText);
	linkText = axe.commons.text.sanitize(linkText);

	return (parentText.length > linkText.length);
};