Easy-to-use and robust function that removes all HTML formatting from an element by replacing its contents with a single Text node. This does not remove any CSS styling applied to the parent element.

removeFormatting.js

/*
USAGE:
	void removeFormatting(Element)

RESULT:
	The provided element now contains a single Text node, whose value is
	the concatenation of all the Text nodes in the original element's hierarchy
*/

// Used internally. Empties the element and returns the concatenated text as a String
function _removeFormatting(el) {
	var text = "";

	var child;
	while (child = el.firstChild) {
		if (child.nodeType === Node.TEXT_NODE)
			text += child.nodeValue;
		else if (child.nodeType === Node.ELEMENT_NODE)
			text += _removeFormatting(child);
		el.removeChild(child);
	}

	return text;
}

function removeFormatting(el) {
	el.appendChild(document.createTextNode(_removeFormatting(el)));
}