Feature Unique Prefix set

[NDH]

I'm using this method to populate a treeView of keys -> leafs -> values, in a utility UI.

/** 
 * returns a list of unique key-tuple prefixes 
 * an empty tuple (array) returns all `root` prefixes 
 */
export async function prefixes(prefix?: any): Promise<Set<any>> {
   const pre = (prefix) ? [prefix] : []
   let keys: Set<any> = new Set()
   const entries = connection.list({prefix:pre})
   for await (const entry of entries) {
      keys.add(entry.key[0]) 
   }
   return keys
}

I discovered an empty tuple returns all root prefixes from KV table.

[Kitson Kelly]

The challenge is that not all Deno.KvKeyParts are primitive values within JavaScript, so your code would work as long as you don't use Uint8Array which is a valid KvKeyPart, so you would end up with an entry for every key, so if the key part is Uint8Array uniques would only be available by comparing any byte arrays in the set by iterating over it.

But I think I can add something that works in every situation.