From bb86adef8cf6d98f0272a20c3bdf3b0262b74a14 Mon Sep 17 00:00:00 2001
From: Peter Sutherland <peter.sutherland@ometria.com>
Date: Tue, 17 Jan 2017 12:07:19 +0000
Subject: [PATCH] Add ability to create comment nodes

---
 src/htmldomapi.ts |  6 ++++++
 src/snabbdom.ts   |  7 ++++++-
 test/core.js      | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/src/htmldomapi.ts b/src/htmldomapi.ts
index 6d6906b..3dc6fcf 100644
--- a/src/htmldomapi.ts
+++ b/src/htmldomapi.ts
@@ -2,6 +2,7 @@ export interface DOMAPI {
   createElement: (tagName: any) => HTMLElement;
   createElementNS: (namespaceURI: string, qualifiedName: string) => Element;
   createTextNode: (text: string) => Text;
+  createComment: (text: string) => Comment;
   insertBefore: (parentNode: Node, newNode: Node, referenceNode: Node | null) => void;
   removeChild: (node: Node, child: Node) => void;
   appendChild: (node: Node, child: Node) => void;
@@ -23,6 +24,10 @@ function createTextNode(text: string): Text {
   return document.createTextNode(text);
 }
 
+function createComment(text: string): Comment {
+  return document.createComment(text);
+}
+
 function insertBefore(parentNode: Node, newNode: Node, referenceNode: Node | null): void {
   parentNode.insertBefore(newNode, referenceNode);
 }
@@ -55,6 +60,7 @@ export const htmlDomApi = {
   createElement,
   createElementNS,
   createTextNode,
+  createComment,
   insertBefore,
   removeChild,
   appendChild,
diff --git a/src/snabbdom.ts b/src/snabbdom.ts
index e89b66b..081c8b9 100644
--- a/src/snabbdom.ts
+++ b/src/snabbdom.ts
@@ -81,7 +81,12 @@ export function init(modules: Array<Partial<Module>>, domApi?: DOMAPI) {
       }
     }
     let children = vnode.children, sel = vnode.sel;
-    if (sel !== undefined) {
+    if (sel === '!') {
+      if (isUndef(vnode.text)) {
+        vnode.text = '';
+      }
+      vnode.elm = api.createComment(vnode.text as string);
+    } else if (sel !== undefined) {
       // Parse selector
       const hashIdx = sel.indexOf('#');
       const dotIdx = sel.indexOf('.', hashIdx);
diff --git a/test/core.js b/test/core.js
index 13435b4..1e5d590 100644
--- a/test/core.js
+++ b/test/core.js
@@ -64,6 +64,11 @@ describe('snabbdom', function() {
       var vnode = h('a', {}, 'I am a string');
       assert.equal(vnode.text, 'I am a string');
     });
+    it('can create vnode for comment', function() {
+      var vnode = h('!', 'test');
+      assert.equal(vnode.sel, '!');
+      assert.equal(vnode.text, 'test');
+    });
   });
   describe('created element', function() {
     it('has tag', function() {
@@ -165,6 +170,11 @@ describe('snabbdom', function() {
       assert.equal(elm.id, 'id');
       assert.equal(elm.className, 'class');
     });
+    it('can create comments', function() {
+      elm = patch(vnode0, h('!', 'test')).elm;
+      assert.equal(elm.nodeType, document.COMMENT_NODE);
+      assert.equal(elm.textContent, 'test');
+    });
   });
   describe('patching an element', function() {
     it('changes the elements classes', function() {
@@ -497,6 +507,30 @@ describe('snabbdom', function() {
         elm = patch(vnode1, vnode2).elm;
         assert.equal(elm.childNodes[0].textContent, 'Text2');
       });
+      it('handles unmoved comment nodes', function() {
+        var vnode1 = h('div', [h('!', 'Text'), h('span', 'Span')]);
+        var vnode2 = h('div', [h('!', 'Text'), h('span', 'Span')]);
+        elm = patch(vnode0, vnode1).elm;
+        assert.equal(elm.childNodes[0].textContent, 'Text');
+        elm = patch(vnode1, vnode2).elm;
+        assert.equal(elm.childNodes[0].textContent, 'Text');
+      });
+      it('handles changing comment text', function() {
+        var vnode1 = h('div', [h('!', 'Text'), h('span', 'Span')]);
+        var vnode2 = h('div', [h('!', 'Text2'), h('span', 'Span')]);
+        elm = patch(vnode0, vnode1).elm;
+        assert.equal(elm.childNodes[0].textContent, 'Text');
+        elm = patch(vnode1, vnode2).elm;
+        assert.equal(elm.childNodes[0].textContent, 'Text2');
+      });
+      it('handles changing empty comment', function() {
+        var vnode1 = h('div', [h('!'), h('span', 'Span')]);
+        var vnode2 = h('div', [h('!', 'Test'), h('span', 'Span')]);
+        elm = patch(vnode0, vnode1).elm;
+        assert.equal(elm.childNodes[0].textContent, '');
+        elm = patch(vnode1, vnode2).elm;
+        assert.equal(elm.childNodes[0].textContent, 'Test');
+      });
       it('prepends element', function() {
         var vnode1 = h('div', [h('span', 'World')]);
         var vnode2 = h('div', [h('span', 'Hello'), h('span', 'World')]);