Replace in DOM textNodes

example.js

// Early version of the Acronym Helper I'm working on.
(function (global) {
	"use strict";
	var $ = global.jQuery,
		acronyms = {
			'FAQ' : 'Frequently Asked Questions',
			'TIL' : 'Today I Learned',
			'ITT' : 'In This Thread',
			'SRS' : 'A Load of Dingo\'s Kidneys'
		};
	function lookup(acronym, location) {
		// This is intended to do a complex lookup involving context.  For now, it just returns the result of a HashMap.
		return acronyms[acronym];
	}
	$(function () {
		$(global.document.body).replaceInText(/(\W)([A-Z]{2,5})(\W)/, function (fullMatch, sym1, acronym, sym2) {
			var acr = lookup(acronym, global.window.location.toString()),
				elem = $('<span>')
					.addClass('acronym-helper')
					.attr({
						'data-acronym' : acronym,
						title: 'Original: ' + acronym
					})
					.text(acr || acronym),
				ret = [sym1, elem, sym2];
			if (!acr) {
				elem.addClass('no-acronym-found');
			}
			return ret;
		});
	});
}(this));

jQuery.replaceText.js

(function (global) {
	"use strict";
	var $ = global.jQuery;
	function toString(obj) {
		return obj ? (obj.toString || Object.prototype.toString).call(obj) : '';
	}
	/**
		Is this a DOM node?
		@param	Object	obj javascript varable to test for node-ness
	*/
	$.isNode = global.Node ?
			function (obj) {
				return obj instanceof global.Node;
			} :
			function (obj) {
				return (typeof obj === "object") &&
					(obj.nodeType) &&
					(obj.nodeType !== undefined) &&
					(obj.hasChildNodes instanceof Function);
			};
	/**
		Get all text nodes descendent from a given node
	*/
	$.fn.textNodes = function () {
		var ret = [];
		this.each(function () {
			var node = this.firstChild;
			while (node !== null) {
				if (node.nodeType === 3) {
					ret.push(node);
				} else {
					ret = ret.concat($(node).textNodes().toArray());
				}
				node = node.nextSibling;
			}
		});
		return $($.map(ret, function (n) { return n; }));
	};
	/**
		Flatten a jQuery vector into a single layer
	*/
	$.fn.flatten = function () {
		var ret = [];
		this.each(function () {
			if (this instanceof $) {
				ret = ret.concat(this.toArray());
			} else if ($.isArray(this)) {
				ret = ret.concat(this);
			} else {
				ret.push(this);
			}
		});
		return $(ret);
	};
	/**
		Globally replace a regular expression with a string or with the result of a function call, but only within the text node descendents of a node
		@param RegExp	pattern	Pattern to match against
		@param String	replacement	replacement pattern
		@param Function	replacement	function that is called with the content of a match, the return value of which is used to replace the matched string.  This method should return a string, node, array of mixed strings and nodes, or jQuery object, representing what should be replaced.
		@info Important: String return values get cast to TextNodes, not used as HTML. If you wish to return HTML, return $(myHTML), rather than myHTML.
		@return	jQuery original jQuery object (chainable).
	*/
	$.fn.replaceInText = function (pattern, replacement) {
		this.textNodes().each(function () {
			var i, acronym, right, mid,
				parent = this.parentNode,
				document = this.ownerDocument,
				content = this.textContent,
				nodes = [];
			while (-1 !== (i = content.search(pattern))) {
				nodes.push(document.createTextNode(content.substr(0, i)));
				right = content.substr(i);
				mid = right.match(pattern);
				content = right.substr(mid[0].length);
				if (replacement instanceof Function) {
					mid = replacement.apply(this.parentNode, mid);
				} else {
					mid = mid[0].replace(pattern, replacement.toString());
				}

				if (!$.isNode(mid) && !(mid instanceof $) && !$.isArray(mid)) {
					mid = document.createTextNode(toString(mid));
				}
				if (!(mid instanceof $)) {
					mid = $(mid);
				}

				mid = mid.flatten();
				nodes = nodes.concat(mid.flatten().toArray());
			}
			if (nodes.length) {
				nodes.push(document.createTextNode(content));
				parent = this.parentNode;
				parent.replaceChild(nodes[0], this);
				for (i = 1; i < nodes.length; i += 1) {
					if (!$.isNode(nodes[i])) {
						nodes[i] = document.createTextNode(nodes[i]);
					}
					if (nodes[i - 1].nextSibling) {
						parent.insertBefore(nodes[i], nodes[i - 1].nextSibling);
					} else {
						parent.appendChild(nodes[i]);
					}
				}
			}
		});
		return this;
	};
}(this));