Move <pre> data attributes to <code> blocks

[gabyx]

I am using the following code to move all data-* attributes from <pre> tags onto <code> blocks before Reveal.intialize(...):

function moveDataAttributesToCodeElement() {
  const codeElements = document.querySelectorAll("pre > code")
  codeElements.forEach((code, index) => {
    console.log(
      `Moving all 'data-' attributes of code block ${index} to <code>`,
      code,
    )
    const pre = code.parentNode
    console.log(pre)

    Array.from(pre.attributes).forEach((attr) => {
      if (attr.name.startsWith("data-")) {
        code.setAttribute(attr.name, attr.value)
        pre.removeAttribute(attr.name)
      }
    })
  })
}

This works nicely. But somehow data-fragment-index="1" gets changed to ="0" with this initialization function:

      moveDataAttributesToCodeElement()

      // Full list of configuration options available at:
      // https://revealjs.com/config/
      Reveal.initialize({
        plugins: [
          RevealNotes,
          RevealSearch,
          RevealZoom,
          RevealHighlight,
          RevealMath.MathJax3,
          RevealMenu
        ]
      })

I am wondering what I am doing wrong when changeing the DOM just before Reveal initializes. It seems to not take up that
changes correctly?

Is there a better approach?