This is a little hard to scan. I think that a reduce would work wonders here.

I agree with felix this is a little hard to scan. I think the reasons are:

• meetsDeleteConditions and toDelete are confusingly named, e.g. how can you meet delete conditions if type isn't separator?
• visibleItems requires a little thought before you can tell how the loop will behave in edge cases

I'm not thinking functionally enough to see how a reduce would work cleanly here and would love enlightenment on this, no snark intended 😄

After poking around with a few approaches, the clearest I came up with was (untested):

function removeExtraSeparators(items) {
  // remove invisible items 
  items = items.filter(e => e.visible !== false)
  // fold adjacent separators together
  items = items.filter((e, idx, arr) => e.type !== 'separator' || idx==0 || arr[idx-1].type!=='separator')
  // remove edge separators
  return items.filter((e, idx, arr) => e.type !== 'separator' || (idx!=0 && idx!=arr.length-1))
}

Marking as Request Changes for cleanup to this section, but the above code is just a suggestion, not a requirement

I agree with felix this is a little hard to scan. I think the reasons are:

• meetsDeleteConditions and toDelete are confusingly named, e.g. how can you meet delete conditions if type isn't separator?
• visibleItems requires a little thought before you can tell how the loop will behave in edge cases

I'm not thinking functionally enough to see how a reduce would work cleanly here and would love enlightenment on this, no snark intended 😄

After poking around with a few approaches, the clearest I came up with was (untested):

function removeExtraSeparators(items) {
  // remove invisible items 
  items = items.filter(e => e.visible !== false)
  // fold adjacent separators together
  items = items.filter((e, idx, arr) => e.type !== 'separator' || idx==0 || arr[idx-1].type!=='separator')
  // remove edge separators
  return items.filter((e, idx, arr) => e.type !== 'separator' || (idx!=0 && idx!=arr.length-1))
}

Marking as Request Changes for cleanup to this section, but the above code is just a suggestion, not a requirement

Another good edge case to test for would be [ sep, sep, a, b, c, sep, sep ] -> [ a, b, c ]