How to format selection instead of whole line?

[robFraser1111]

I've created a custom plugin and can format the whole paragraph using $setBlocksType.

But I want to format just the selected text. I've currently got as far as the below.

I'm also getting this type error: node.replace is not a function

Thanks.

const formatDropCap = (e: React.MouseEvent<HTMLButtonElement>) => {
  e.preventDefault()
  editor.update(() => {
    const selection = $getSelection()

    if ($isRangeSelection(selection)) {
      const anchor = selection.anchor
      const focus = selection.focus
      const textNodes = selection.getNodes()

      // Format each text node
      textNodes.forEach((node) => {
        node = node.splitText(anchor.offset, focus.offset)[1]

        if ($isDropCapNode(node)) {
          node.replace($createParagraphNode(), true)
        } else {
          node.replace($createDropCapNode(), true)
        }
      })
    }
  })