set cookie for sidebar preference

js/mixins/toggle.js

@@ -0,0 +1,23 @@
+export default {
+  data: function() {
+    return {
+      isVisible: this.defaultVisible,
+    }
+  },
+
+  render: function(createElement) {
+    return createElement(this.$vnode.data.tag, [
+      this.$scopedSlots.default({
+        isVisible: this.isVisible,
+        toggle: this.toggle,
+      }),
+    ])
+  },
+
+  methods: {
+    toggle: function(e) {
+      e.preventDefault()
+      this.isVisible = !this.isVisible
+    },
+  },
+}