From 8aa201b9ade9ed7b282a82f291f660c1113e1896 Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Wed, 31 May 2017 11:31:12 -0700
Subject: [PATCH] Special-case undefined textarea.value same as input. Fixes
 #4630

---
 lib/mixins/property-effects.html         | 3 ++-
 test/unit/property-effects-elements.html | 1 +
 test/unit/property-effects.html          | 8 ++++++++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/mixins/property-effects.html b/lib/mixins/property-effects.html
index 9dc5d3273e..e23d6fb299 100644
--- a/lib/mixins/property-effects.html
+++ b/lib/mixins/property-effects.html
@@ -598,7 +598,8 @@
     if (binding.kind !== 'attribute') {
       // Some browsers serialize `undefined` to `"undefined"`
       if (binding.target === 'textContent' ||
-          (node.localName == 'input' && binding.target == 'value')) {
+          (binding.target === 'value' &&
+            (node.localName === 'input' || node.localName === 'textarea'))) {
         value = value == undefined ? '' : value;
       }
     }
diff --git a/test/unit/property-effects-elements.html b/test/unit/property-effects-elements.html
index 0d9853cde0..34e9113892 100644
--- a/test/unit/property-effects-elements.html
+++ b/test/unit/property-effects-elements.html
@@ -63,6 +63,7 @@
       <s id="computedContent">{{computeFromTrickyLiterals(3, 'tricky\,\'zot\'')}}</s>
       <s id="computedContent2">{{computeFromTrickyLiterals("(",3)}}</s>
       <input id="boundInput" value="{{text::input}}">
+      <textarea id="boundTextArea" value="{{text::input}}"></textarea>
       <div id="compound1">{{cpnd1}}{{cpnd2}}{{cpnd3.prop}}{{computeCompound(cpnd4, cpnd5, 'literalComputed')}}</div>
       <div id="compound2">
         literal1 {{cpnd1}} literal2 {{cpnd2}}{{cpnd3.prop}} literal3 {{computeCompound(cpnd4, cpnd5, 'literalComputed')}} literal4
diff --git a/test/unit/property-effects.html b/test/unit/property-effects.html
index bc6404e0c0..2632cf032b 100644
--- a/test/unit/property-effects.html
+++ b/test/unit/property-effects.html
@@ -45,6 +45,14 @@
     assert.equal(el.$.boundInput.value, '', 'undefined input value not blank');
   });
 
+  test('undefined textarea value', function() {
+    assert.equal(el.$.boundTextArea.value, '', 'undefined textarea value not blank');
+    el.text = 'this is a test';
+    assert.equal(el.$.boundTextArea.value, 'this is a test', 'binding to textarea didn\'t go');
+    el.text = undefined;
+    assert.equal(el.$.boundTextArea.value, '', 'undefined textarea value not blank');
+  });
+
   test('id is bindable', function() {
     assert.equal(el.root.querySelector('span[idtest]').id, 'span', 'id bound to <span> not found');
   });