The missing ReplaceAttrsStep for prosemirror

import 'prosemirror-replaceattrs' /// somewhere in your project

tr.replaceAttrs(pos, attrs)

In prosemirror, in order to update attributes of a node, you must delete it and replace with a new node with updated attributes. Something like this:

state.tr.setNodeMarkup(state.selection.from, undefined, attrs)
/// or
newNode = node.copy()
newNode.attrs = attrs
state.tr.replaceWith(pos, pos + 1, newNode)

While this works perfectly, during collaboration it does not go well with undo history. Suppose user A inserts an image node and user B updates alt attribute of that image node. When user A hits undo, it should remove the inserted image, but it will not if you've replaced the entire node. This ReplaceAttrsStep solves that problem if you use it to update attributes of a node.