Hello,

I asked for a feature request in astrojs regarding the Copy Button they use on their code blocks. cf withastro/starlight#2993

I was told that this Copy Button feature comes from expressive code so I open this issue to discuss the feasability of this request.

currently on astrojs/starlight, when a diff code block is copied in the clipboard, it contains all the code that is shown on screen, but without the +/- of the diffed lines. so in the clipboard we get non working code.

I would suggest that when used in diff mode

• the lines starting with + are kept, but without the + as it works today
• the lines starting with - are removed and not added to the clipboard

there is an example I posted in the starlight repo. let me copy it here for easier reference :

when

is copied to the clipboard, i get

function ceciEstDuJavaScript() {
  // Ce bloc entier utilise la coloration syntaxique JavaScript,
  // et nous pouvons toujours y ajouter des marqueurs de différence !
  console.log('Ancien code à supprimer')
  console.log('Nouveau code brillant !')
}

while I would expect

function ceciEstDuJavaScript() {
  // Ce bloc entier utilise la coloration syntaxique JavaScript,
  // et nous pouvons toujours y ajouter des marqueurs de différence !
  console.log('Nouveau code brillant !')
}

Do you think this would be an interesting feature to add ?
can you tell me where the removal of the +/- is done in the code ; I could look at it and maybe propose a PR if it is not too complicated (this would be my first expressive-code PR)