修改结构

docs/gitbook/gitbook-plugin-chapter-fold/chapter-fold.css

@@ -0,0 +1,29 @@
+.book .book-summary .chapter > .articles {
+	overflow: hidden;
+	max-height: 0px;
+}
+
+.book .book-summary .chapter.expanded > .articles {
+	max-height: 9999px;
+}
+
+.book .book-summary .exc-trigger {
+	position: absolute;
+  	left: 12px;
+  	top: 12px;
+}
+
+.book .book-summary ul.summary li a,
+.book .book-summary ul.summary li span {
+	padding-left: 30px;
+}
+
+.book .book-summary .exc-trigger:before {
+  	content: "\f105";
+}
+
+.book .book-summary .expanded > a .exc-trigger:before,
+.book .book-summary .expanded > span .exc-trigger:before {
+	content: "\f107";
+}
+

docs/gitbook/gitbook-plugin-chapter-fold/chapter-fold.js

@@ -0,0 +1,67 @@
+require(['gitbook', 'jQuery'], function(gitbook, $) {
+  var TOGGLE_CLASSNAME = 'expanded',
+      CHAPTER = '.chapter',
+      ARTICLES = '.articles',
+      TRIGGER_TEMPLATE = '<i class="exc-trigger fa"></i>',
+      LS_NAMESPACE = 'expChapters';
+  var init = function () {
+    // adding the trigger element to each ARTICLES parent and binding the event
+    var chapterLink = $(ARTICLES).parent(CHAPTER).children('a');
+    chapterLink.append($(TRIGGER_TEMPLATE));
+    chapterLink.on('click', function (e) {
+      e.preventDefault();
+      //e.stopPropagation();
+      toggle($(e.target).closest(CHAPTER));
+    });  
+
+    expand(lsItem());
+    //expand current selected chapter with it's parents
+    collapse($(CHAPTER));
+    var activeChapter = $(CHAPTER + '.active');
+    expand(activeChapter);
+    expand(activeChapter.parents(CHAPTER));
+  } 
+  //on page.change will happend the function.
+
+  var toggle = function ($chapter) {
+    if ($chapter.hasClass('expanded')) {
+      collapse($chapter);
+    } else {
+      expand($chapter);
+      //$chapter.addClass('active').siblings().removeClass('active');
+    }
+  }
+  var collapse = function ($chapter) {
+    if ($chapter.length && $chapter.hasClass(TOGGLE_CLASSNAME)) {
+      $chapter.removeClass(TOGGLE_CLASSNAME);
+      lsItem($chapter);
+    }
+  }
+  var expand = function ($chapter) {
+    if ($chapter.length && !$chapter.hasClass(TOGGLE_CLASSNAME)) {
+      $chapter.addClass(TOGGLE_CLASSNAME);
+      lsItem($chapter);
+    }
+  }
+  var lsItem = function () {
+    var map = JSON.parse(localStorage.getItem(LS_NAMESPACE)) || {}
+    if (arguments.length) {
+      var $chapters = arguments[0];
+      $chapters.each(function (index, element) {
+        var level = $(this).data('level');
+        var value = $(this).hasClass(TOGGLE_CLASSNAME);
+        map[level] = value;
+      })
+      localStorage.setItem(LS_NAMESPACE, JSON.stringify(map));
+    } else {
+      return $(CHAPTER).map(function(index, element){
+        if (map[$(this).data('level')]) {
+          return this;
+        }
+      })
+    }
+  }
+  gitbook.events.bind('page.change', function() {
+    init()
+  }); 
+});