feat: change TOC plugin to tocbot (#774)

_javascript/modules/components/toc.js

@@ -0,0 +1,11 @@
+export function toc() {
+  // see: https://github.com/tscanlin/tocbot#usage
+  tocbot.init({
+    tocSelector: '#toc',
+    contentSelector: '.post-content',
+    ignoreSelector: '[data-toc-skip]',
+    headingSelector: 'h2, h3',
+    orderedList: false,
+    scrollSmooth: false
+  });
+}

_javascript/modules/plugins.js

@@ -4,3 +4,4 @@ export { imgExtra } from './components/img-extra';
 export { initLocaleDatetime } from './components/locale-datetime';
 export { initPageviews } from './components/pageviews';
 export { smoothScroll } from './components/smooth-scroll';
+export { toc } from './components/toc';

_javascript/post.js

@@ -4,7 +4,8 @@ import {
   initLocaleDatetime,
   initClipboard,
   smoothScroll,
-  initPageviews
+  initPageviews,
+  toc
 } from './modules/plugins';
 
 basic();
@@ -13,5 +14,6 @@ initTopbar();
 imgExtra();
 initLocaleDatetime();
 initClipboard();
-smoothScroll();
+toc();
+smoothScroll(); // must be called after toc is created
 initPageviews();