How to change blockType by pressing keyboard

[qirong77]

I want to change the blocktype when I tag something.
For example , I want to change the current blocktype to 'header-one' when I press 'x' in my keyboard, here is my code

  const handleBefeforeInput = (
    chars: string,
    editorState: EditorState,
    eventTimeStamp: number
  ) => {
    if (true) {
      if (chars === 'x') {
    setEditorState(RichUtils.toggleBlockType(editorState, 'header-one'))
      }
      return 'not-handled'
    } else {
      return 'handled'
    }
  }

It works at the first time , but when I press enter or tag in other block , the blocktype turn to 'unstyled'. I dont know how to fix this problem , can anybody help me ,thanks