From c260725e6506adf64923cc343c407f1e4018c302 Mon Sep 17 00:00:00 2001
From: Ian Storm Taylor <ian@ianstormtaylor.com>
Date: Wed, 17 May 2017 09:14:33 -0700
Subject: [PATCH] add support for skipping elements in html serializer, closes
 #821

---
 History.md                                    | 11 ++++++++++
 src/serializers/html.js                       | 15 ++++++++------
 .../html/deserialize/skip-element/index.js    | 20 +++++++++++++++++++
 .../html/deserialize/skip-element/input.html  |  2 ++
 .../html/deserialize/skip-element/output.yaml |  8 ++++++++
 5 files changed, 50 insertions(+), 6 deletions(-)
 create mode 100644 test/serializers/fixtures/html/deserialize/skip-element/index.js
 create mode 100644 test/serializers/fixtures/html/deserialize/skip-element/input.html
 create mode 100644 test/serializers/fixtures/html/deserialize/skip-element/output.yaml

diff --git a/History.md b/History.md
index faee9aeec..1b36b3cbd 100644
--- a/History.md
+++ b/History.md
@@ -4,6 +4,17 @@ This document maintains a list of changes to Slate with each new version. Until
 
 ---
 
+
+### `0.20.0` — May 17, 2017
+
+###### BREAKING CHANGES
+
+- **Returning `null` from the `Html` serializer skips the element.** Previously, `null` and `undefined` had the same behavior of skipping the rule and trying the rest of the rules. Now if you explicitly return `null` it will skip the element itself.
+
+
+---
+
+
 ### `0.19.0` — March 3, 2017
 
 ###### BREAKING CHANGES
diff --git a/src/serializers/html.js b/src/serializers/html.js
index 134c6f21d..2bb912ed4 100644
--- a/src/serializers/html.js
+++ b/src/serializers/html.js
@@ -159,11 +159,6 @@ class Html {
         case 'object':
           nodes.push(node)
           break
-        case 'null':
-        case 'undefined':
-          return
-        default:
-          throw new Error(`A rule returned an invalid deserialized representation: "${node}".`)
       }
     })
 
@@ -196,8 +191,16 @@ class Html {
 
     for (const rule of this.rules) {
       if (!rule.deserialize) continue
+
       const ret = rule.deserialize(element, next)
-      if (!ret) continue
+      if (ret === undefined) continue
+      if (ret === null) break
+
+      const type = typeOf(ret)
+      if (type != 'array' && type != 'object') {
+        throw new Error(`A rule returned an invalid deserialized representation: "${node}".`)
+      }
+
       node = ret.kind == 'mark' ? this.deserializeMark(ret) : ret
       break
     }
diff --git a/test/serializers/fixtures/html/deserialize/skip-element/index.js b/test/serializers/fixtures/html/deserialize/skip-element/index.js
new file mode 100644
index 000000000..6beb73d9d
--- /dev/null
+++ b/test/serializers/fixtures/html/deserialize/skip-element/index.js
@@ -0,0 +1,20 @@
+
+export default {
+  rules: [
+    {
+      deserialize(el, next) {
+        if (el.tagName == 'div') {
+          return null
+        }
+      }
+    },
+    {
+      deserialize(el, next) {
+        return {
+          kind: 'block',
+          type: 'paragraph',
+        }
+      }
+    },
+  ]
+}
diff --git a/test/serializers/fixtures/html/deserialize/skip-element/input.html b/test/serializers/fixtures/html/deserialize/skip-element/input.html
new file mode 100644
index 000000000..196f72ae8
--- /dev/null
+++ b/test/serializers/fixtures/html/deserialize/skip-element/input.html
@@ -0,0 +1,2 @@
+<p></p>
+<div></div>
diff --git a/test/serializers/fixtures/html/deserialize/skip-element/output.yaml b/test/serializers/fixtures/html/deserialize/skip-element/output.yaml
new file mode 100644
index 000000000..a3397f7b2
--- /dev/null
+++ b/test/serializers/fixtures/html/deserialize/skip-element/output.yaml
@@ -0,0 +1,8 @@
+
+data: {}
+nodes:
+  - type: paragraph
+    isVoid: false
+    data: {}
+    nodes:
+      - characters: []