NIP-25

Reactions

draft optional author:jb55

A reaction is a kind 7 event that is used to react to other events.

The generic reaction, represented by the content set to a + string, SHOULD be interpreted as a "like" or "upvote".

A reaction with content set to - SHOULD be interpreted as a "dislike" or "downvote". It SHOULD NOT be counted as a "like", and MAY be displayed as a downvote or dislike on a post. A client MAY also choose to tally likes against dislikes in a reddit-like system of upvotes and downvotes, or display them as separate tallies.

The content MAY be an emoji, or NIP-30 custom emoji in this case it MAY be interpreted as a "like" or "dislike", or the client MAY display this emoji reaction on the post. If the content is an empty string then the client should consider it a "+".

Tags

The reaction event SHOULD include e and p tags from the note the user is reacting to. This allows users to be notified of reactions to posts they were mentioned in. Including the e tags enables clients to pull all the reactions associated with individual posts or all the posts in a thread.

The last e tag MUST be the id of the note that is being reacted to.

The last p tag MUST be the pubkey of the event being reacted to.

The reaction event MAY include a k tag with the stringified kind number of the reacted event as its value.

Example code

func make_like_event(pubkey: String, privkey: String, liked: NostrEvent) -> NostrEvent {
    var tags: [[String]] = liked.tags.filter { 
    	tag in tag.count >= 2 && (tag[0] == "e" || tag[0] == "p") 
    }
    tags.append(["e", liked.id])
    tags.append(["p", liked.pubkey])
    tags.append(["k", liked.kind])
    let ev = NostrEvent(content: "+", pubkey: pubkey, kind: 7, tags: tags)
    ev.calculate_id()
    ev.sign(privkey: privkey)
    return ev
}

Custom Emoji Reaction

The client may specify a custom emoji (NIP-30) :shortcode: in the reaction content. The client should refer to the emoji tag and render the content as an emoji if shortcode is specified.

{
  "kind": 7,
  "content": ":soapbox:",
  "tags": [
    ["emoji", "soapbox", "https://gleasonator.com/emoji/Gleasonator/soapbox.png"]
  ],
  "pubkey": "79c2cae114ea28a981e7559b4fe7854a473521a8d22a66bbab9fa248eb820ff6",
  "created_at": 1682790000
}

The content can be set only one :shortcode:. And emoji tag should be one.