Another variant that might be useful, especially for copy&paste of posted code is just turning the code blocks into textarea form fields:

<script>
window.addEventListener( "DOMContentLoaded", ( event ) => {
  document.querySelectorAll('.codeblock .codetext font').forEach(funct
+ion (currentValue, currentIndex, listObj) {
    currentValue.innerHTML = '<textarea class="blockofcode">' + curren
+tValue.innerHTML + '</textarea>';
  });
} );
</script>
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