Added a previous_page_button preference option and made switching between the first page and previous page buttons possible

src/invidious/views/channel.ecr

@@ -21,7 +21,8 @@
   page_nav_html = IV::Frontend::Pagination.nav_ctoken(locale,
     base_url: relative_url,
     ctoken: next_continuation,
-    first_page: continuation.nil?
+    first_page: continuation.nil?,
+    previous_page_button: env.get("preferences").as(Preferences).previous_page_button
   )
 %>
 
@@ -41,6 +42,10 @@
 <link rel="alternate" type="application/rss+xml" title="RSS" href="/feed/channel/<%= ucid %>" />
 <%- end -%>
 
+<%- if env.get("preferences").as(Preferences).previous_page_button -%>
+<script src="/js/pagination.js?v=<%= ASSET_COMMIT %>"></script>
+<%- end -%>
+
 <link rel="alternate" href="<%= youtube_url %>">
 <title><%= author %> - Invidious</title>
 <% end %>

src/invidious/views/components/items_paginated.ecr

@@ -8,4 +8,14 @@
 
 <%= page_nav_html %>
 
+<script id="pagination-data" type="application/json">
+<%=
+{
+   "next_page" => translate(locale, "Next page"),
+   "prev_page" => translate(locale, "Previous page"),
+   "is_rtl"    => locale_is_rtl?(locale)
+}.to_json
+%>
+</script>
+
 <script src="/js/watched_indicator.js"></script>

src/invidious/views/user/preferences.ecr

@@ -189,6 +189,12 @@
                     </select>
                 <% end %>
             </div>
+
+	    <div class="pure-control-group">
+               <label for="previous_page_button"><%= translate(locale, "preferences_previous_page_button_label") %></label>
+	       <input name="previous_page_button" id="previous_page_button" type="checkbox" <% if preferences.previous_page_button %>checked<% end %>>
+	    </div>
+
             <% if env.get? "user" %>
                 <div class="pure-control-group">
                     <label for="show_nick"><%= translate(locale, "preferences_show_nick_label") %></label>