I decided to implement the approach I outlined in my comment to my other answer: traversing nodes within the selected range and removing particular nodes (in this case, based on tag name).
Here's the full demo. It won't work in IE <= 8 (which lacks DOM Range and Selection support) but will in everything other major current browser. One problem is that the selection isn't always preserved, but that isn't too hard to achieve.
http://jsfiddle.net/gF3sa/1/
This example includes modified range traversal code from elsewhere on SO.
function nextNode(node) {
if (node.hasChildNodes()) {
return node.firstChild;
} else {
while (node && !node.nextSibling) {
node = node.parentNode;
}
if (!node) {
return null;
}
return node.nextSibling;
}
}
function getRangeSelectedNodes(range, includePartiallySelectedContainers) {
var node = range.startContainer;
var endNode = range.endContainer;
var rangeNodes = [];
// Special case for a range that is contained within a single node
if (node == endNode) {
rangeNodes = [node];
} else {
// Iterate nodes until we hit the end container
while (node && node != endNode) {
rangeNodes.push( node = nextNode(node) );
}
// Add partially selected nodes at the start of the range
node = range.startContainer;
while (node && node != range.commonAncestorContainer) {
rangeNodes.unshift(node);
node = node.parentNode;
}
}
// Add ancestors of the range container, if required
if (includePartiallySelectedContainers) {
node = range.commonAncestorContainer;
while (node) {
rangeNodes.push(node);
node = node.parentNode;
}
}
return rangeNodes;
}
function getSelectedNodes() {
var nodes = [];
if (window.getSelection) {
var sel = window.getSelection();
for (var i = 0, len = sel.rangeCount; i < len; ++i) {
nodes.push.apply(nodes, getRangeSelectedNodes(sel.getRangeAt(i), true));
}
}
return nodes;
}
function replaceWithOwnChildren(el) {
var parent = el.parentNode;
while (el.hasChildNodes()) {
parent.insertBefore(el.firstChild, el);
}
parent.removeChild(el);
}
function removeSelectedElements(tagNames) {
var tagNamesArray = tagNames.toLowerCase().split(",");
getSelectedNodes().forEach(function(node) {
if (node.nodeType == 1 &&
tagNamesArray.indexOf(node.tagName.toLowerCase()) > -1) {
// Remove the node and replace it with its children
replaceWithOwnChildren(node);
}
});
}
removeSelectedElements("h1,h2,h3,h4,h5,h6");