nips/25.md

NIP-25
======

Reactions
---------

`draft` `optional` `author:jb55`

A reaction is a `kind 7` note that is used to react to other notes.

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](30.md) 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.

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.

Example code

```swift
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])
    let ev = NostrEvent(content: "+", pubkey: pubkey, kind: 7, tags: tags)
    ev.calculate_id()
    ev.sign(privkey: privkey)
    return ev
}