Create a new popup to read the current selection

read-selection.js

(function() {

	function parents(node) {
		var el = node,
			els = [];
		while ( el && (el = el.parentNode) ) {
			els.push(el);
		}
		return els;
	}

	var s = getSelection(),
		from = s.baseNode,
		to = s.extentNode;
	var parents1 = parents(from),
		parents2 = parents(to),
		ancestor;
	outside:
	for ( var i=0, L=parents1.length; i<L; i++ ) {
		for ( var j=0, M=parents2.length; j<M; j++ ) {
			if ( parents1[i] == parents2[j] ) {
				ancestor = parents1[1];
				break outside;
			}
		}
	}
	console.log('common ancestor', ancestor);

	if ( ancestor ) {
		console.log('====' + ancestor.textContent.trim() + '====')
		with ( ancestor.style ) {
			position = 'fixed';
			top = '5%';
			right = '5%';
			bottom = '5%';
			left = '5%';
			outline = 'solid 200px rgba(0, 0, 0, 0.5)';
			background = 'white';
			color = 'black';
		}
	}

})();