fix(ngSanitize): prefer textContent to innerText to avoid layout trashing

innerText depends on styling as it doesn't display hidden elements.
Therefore, it's better to use textContent not to cause unnecessary
reflows. However, IE<9 don't support textContent so the innerText
fallback is necessary.

2 files changed, 58 insertions, 1 deletions

diff --git a/src/ngSanitize/sanitize.js b/src/ngSanitize/sanitize.js
index e669e77a..1e424d69 100644
--- a/src/ngSanitize/sanitize.js
+++ b/src/ngSanitize/sanitize.js
@@ -378,7 +378,12 @@ function decodeEntities(value) {
   var content = parts[2];
   if (content) {
     hiddenPre.innerHTML=content.replace(/</g,"&lt;");
-    content = hiddenPre.innerText || hiddenPre.textContent;
+    // innerText depends on styling as it doesn't display hidden elements.
+    // Therefore, it's better to use textContent not to cause unnecessary
+    // reflows. However, IE<9 don't support textContent so the innerText
+    // fallback is necessary.
+    content = 'textContent' in hiddenPre ?
+      hiddenPre.textContent : hiddenPre.innerText;
   }
   return spaceBefore + content + spaceAfter;
 }
diff --git a/test/ngSanitize/sanitizeSpec.js b/test/ngSanitize/sanitizeSpec.js
index 1958ec0f..fbffbba5 100644
--- a/test/ngSanitize/sanitizeSpec.js
+++ b/test/ngSanitize/sanitizeSpec.js
@@ -411,3 +411,55 @@ describe('HTML', function() {
     });
   });
 });
+
+describe('decodeEntities', function() {
+  var handler, text,
+      origHiddenPre = window.hiddenPre;
+
+  beforeEach(function() {
+    text = '';
+    handler = {
+      start: function() {},
+      chars: function(text_){
+        text = text_;
+      },
+      end: function() {},
+      comment: function() {}
+    };
+    module('ngSanitize');
+  });
+
+  afterEach(function() {
+    window.hiddenPre = origHiddenPre;
+  });
+
+  it('should use innerText if textContent is not available (IE<9)', function() {
+    window.hiddenPre = {
+      innerText: 'INNER_TEXT'
+    };
+    inject(function($sanitize) {
+      htmlParser('<tag>text</tag>', handler);
+      expect(text).toEqual('INNER_TEXT');
+    });
+  });
+  it('should use textContent if available', function() {
+    window.hiddenPre = {
+      textContent: 'TEXT_CONTENT',
+      innerText: 'INNER_TEXT'
+    };
+    inject(function($sanitize) {
+      htmlParser('<tag>text</tag>', handler);
+      expect(text).toEqual('TEXT_CONTENT');
+    });
+  });
+  it('should use textContent even if empty', function() {
+    window.hiddenPre = {
+      textContent: '',
+      innerText: 'INNER_TEXT'
+    };
+    inject(function($sanitize) {
+      htmlParser('<tag>text</tag>', handler);
+      expect(text).toEqual('');
+    });
+  });
+});