After some more searching and trying I found the solution myself! It appears that the best way to do this is by inserting a new block when the split-block keyCommand is fired.
For example:
createEmptyBlock(editorState: Draft.EditorState) {
const newBlock = new Draft.ContentBlock({
key: Draft.genKey(),
type: "unstyled",
text: "",
characterList: Immutable.List()
})
const contentState = editorState.getCurrentContent()
const newBlockMap = contentState.getBlockMap().set(newBlock.getKey(), newBlock)
return Draft.EditorState.push(
editorState,
Draft.ContentState
.createFromBlockArray(newBlockMap.toArray())
.set('selectionAfter', contentState.getSelectionAfter().merge({
anchorKey: newBlock.getKey(),
anchorOffset: 0,
focusKey: newBlock.getKey(),
focusOffset: 0,
isBackward: false,
})) as Draft.ContentState,
"split-block"
)
}
This answer was posted as an edit to the question DraftJS: Reset blockType after return by the OP n9iels under CC BY-SA 3.0.