cross-browser-text-selection.js

cross-browser-text-selection.js

(function (win, doc) {
	function getRangeAtCollapse(range, collapsed) {
		// get range as item
		if (range.item) {
			var rangeItem = range.item(0);
			// return the data
			return { node: rangeItem };
		}
		// get range as text
		var
		rangeA = range.duplicate(),
		rangeB = range.duplicate(),
		i = -1,
		rangeElement, rangeNode, offset;
		// collapse the range to the start or end of the selection
		rangeB.collapse(!!collapsed);
		// get the closest available element node
		rangeElement = rangeB.parentElement();
		// read between the element and the selection
		rangeA.moveToElementText(rangeElement);
		rangeA.setEndPoint('EndToStart', rangeB);
		// get the offset despite a failure to read \r\n
		offset = rangeA.text.replace(/\r\n/gm, '\n').length;
		// get the offset between the textnodes
		while (offset > -1 && i + 1 < rangeElement.childNodes.length) offset -= (rangeElement.childNodes[++i].nodeValue || rangeElement.childNodes[i].innerHTML).length;
		// hey look, the text node
		rangeNode = rangeElement.childNodes[i] || rangeElement;
		// return the data
		return {
			node: rangeNode,
			offset: String(rangeNode.nodeValue || rangeNode.innerHTML || rangeNode.value || '').length + offset
		};
	}

	function getRangeFromDocumentSelection() {
		var
		range = doc.selection.createRange(),
		rangeDataStart = getRangeAtCollapse(range, true),
		rangeDataEnd = getRangeAtCollapse(range, false);
		// return the data
		return {
			node: rangeDataStart.node === rangeDataEnd.node ? rangeDataStart.node : range.parentElement(),
			start: {
				node: rangeDataStart.node,
				offset: rangeDataStart.offset
			},
			end: {
				node: rangeDataEnd.node,
				offset: rangeDataEnd.offset
			}
		};
	}

	function isNodeTextType(node) { return /[348]/.test(node.nodeType); }

	win.textSelection = ('getSelection' in win) ? function () {
		var winGetSelection = win.getSelection(), docActiveElement = doc.activeElement;
		// get range as field
		if ('selectionStart' in docActiveElement) {
			// return the data
			return {
				node: docActiveElement,
				start: {
					node: docActiveElement,
					offset: docActiveElement.selectionStart
				},
				end: {
					node: docActiveElement,
					offset: docActiveElement.selectionEnd
				}
			};
		}
		// get range as text
		if (winGetSelection.rangeCount) {
			var
			range = winGetSelection.getRangeAt(0),
			node = range.commonAncestorContainer,
			start = {
				node: range.startContainer,
				offset: range.startOffset
			},
			end = {
				node: range.endContainer,
				offset: range.endOffset
			};
			//  correct misguided offsets
			if (!isNodeTextType(start.node) && start.offset > start.node.childNodes.length - 1) start.offset = start.node.innerHTML.length;
			if (!isNodeTextType(end.node) && end.offset > end.node.childNodes.length - 1) end.offset = end.node.innerHTML.length;
			// return the data
			return { node: node, start: start, end: end };
		}
	} : ('selection' in doc) ? getRangeFromDocumentSelection : function() {};
})(this, document);