Upvotes.

src/General/Config.coffee

@@ -576,6 +576,10 @@ Config =
         false
         'Thread conversations'
       ]
+      'Upvotes': [
+        true
+        'Upvote posts.'
+      ]
 
   imageExpansion:
     'Fit width': [

src/General/Main.coffee

@@ -410,6 +410,7 @@ Main =
     ['Edit Link',                 QR.oekaki.menu]
     ['Download Link',             DownloadLink]
     ['Archive Link',              ArchiveLink]
+    ['Upvotes',                   Upvotes]
     ['Quote Inlining',            QuoteInline]
     ['Quote Previewing',          QuotePreview]
     ['Quote Backlinks',           QuoteBacklink]

src/Quotelinks/Upvotes.coffee

@@ -0,0 +1,49 @@
+Upvotes =
+  text: '\u305D\u3046\u3060\u306D'
+  count: {}
+
+  init: ->
+    return unless g.VIEW is 'thread' and Conf['Upvotes']
+    Post.callbacks.push
+      name: 'Upvotes'
+      cb:   @node
+
+  node: ->
+    return if @isFetchedQuote or @origin?.isFetchedQuote
+
+    if @isClone
+      @nodes.vote = $ '.upvote', @nodes.info
+      $.on @nodes.vote, 'click', Upvotes.vote
+      return
+
+    a = $.el 'a',
+      className:   'upvote'
+      href:        'javascript:;'
+      textContent: '+'
+    $.add @nodes.info, a
+    @nodes.vote = a
+    $.on a, 'click', Upvotes.vote
+
+    Upvotes.count[@fullID] = 0
+
+    if @quotes.length is 1 and @info.comment.indexOf(Upvotes.text) >= 0
+      Upvotes.increment @quotes[0]
+
+  increment: (fullID) ->
+    return unless fullID of Upvotes.count
+    count = ++Upvotes.count[fullID]
+    post = g.posts[fullID]
+    for post in [post, post.clones...]
+      post.nodes.vote.textContent = "#{Upvotes.text}x#{count}"
+    return
+
+  vote: ->
+    return unless QR.postingIsEnabled
+    QR.quote.call @
+    {com} = QR.nodes
+    text = "#{Upvotes.text}\n"
+    pos = com.selectionStart
+    com.value = com.value[..pos] + text + com.value[pos...]
+    pos += text.length
+    com.setSelectionRange pos, pos
+    $.event 'input', null, com

src/css/style.css

@@ -2084,3 +2084,8 @@ grunt.file.expand('src/Linkification/icons/*.png').map(function(file) {
 :root.gallery-open.fixed #header-bar:not(.autohide) #shortcuts .fa::before {
   visibility: hidden;
 }
+
+/* Upvotes */
+.upvote {
+  margin: 0 4px;
+}