Revision: 5365
Author: [email protected]
Date: Mon Apr 22 11:12:00 2013
Log: Allow overriding inherited properties of Domado objects by
assignment.
https://codereview.appspot.com/8649044
* ExpandoProxyHandler no longer treats defineProperty of a property
name which exists somewhere in the prototype chain differently for
no good reason.
* ExpandoProxyHandler's reimplementation of assignment no longer
acts according to the "override mistake" (needed for ES5/3).
Fixes <https://code.google.com/p/google-caja/issues/detail?id=1650>.
[email protected]
http://code.google.com/p/google-caja/source/detail?r=5365
Modified:
/trunk/src/com/google/caja/plugin/domado.js
/trunk/tests/com/google/caja/plugin/es53-test-domado-dom-guest.html
=======================================
--- /trunk/src/com/google/caja/plugin/domado.js Wed Apr 17 11:08:30 2013
+++ /trunk/src/com/google/caja/plugin/domado.js Mon Apr 22 11:12:00 2013
@@ -689,8 +689,8 @@
if (name === weakMapMagicName) {
if (descriptor.set === null) descriptor.set = undefined;
Object.defineProperty(this, 'weakMapMagic', descriptor);
- } else if (Object.prototype.hasOwnProperty(this.target, name)) {
- // Forwards everything already defined (not expando).
+ } else if (Object.prototype.hasOwnProperty.call(this.target, name)) {
+ // Forward attempted redefinitions of own properties to the target.
return ProxyHandler.prototype.defineProperty.call(this, name,
descriptor);
} else {
@@ -703,8 +703,8 @@
ExpandoProxyHandler.prototype['delete'] = function (name) {
if (name === weakMapMagicName) {
return false;
- } else if (Object.prototype.hasOwnProperty(this.target, name)) {
- // Forwards everything already defined (not expando).
+ } else if (Object.prototype.hasOwnProperty.call(this.target, name)) {
+ // Forward attempted deletions of own properties to the target.
return ProxyHandler.prototype['delete'].call(this, name);
} else {
if (!this.editable) { throw new Error(NOT_EDITABLE); }
@@ -769,11 +769,22 @@
desc = this.getPropertyDescriptor(name);
if (desc) {
if ('writable' in desc) {
- if (desc.writable) {
- // fall through
- } else {
- return false;
- }
+ // The commenting-out of the below code corresponds to "fixing
the
+ // override mistake". For further information, see
+ // Object.prototype.w___ in ES5/3 and makeTamperProof in SES.
+ //
+ // We need to do the 'fix' here because this proxy trap is a
+ // reimplementation of what otherwise would be JS runtime
internal
+ // algorithms, and so not doing the fix would break code which
+ // optimizes on the knowledge that the platform has the fix.
+ // (In particular, cajaVM.def uses nonwritable data properties
instead
+ // of accessor properties whenever possible.)
+ //
+ // if (desc.writable) {
+ // // fall through
+ // } else {
+ // return false;
+ // }
} else { // accessor
if (desc.set) {
desc.set.call(receiver, val);
=======================================
--- /trunk/tests/com/google/caja/plugin/es53-test-domado-dom-guest.html Thu
Apr 18 11:36:23 2013
+++ /trunk/tests/com/google/caja/plugin/es53-test-domado-dom-guest.html Mon
Apr 22 11:12:00 2013
@@ -561,6 +561,26 @@
});
</script>
+<p id="testExpandoOverride" class="testcontainer">
+ testExpandoOverride: can replace methods on instances
+</p>
+<script type="text/javascript">
+ jsunitRegister('testExpandoOverride',
+ function testExpandoOverride() {
+ // Example from Angular -- happens to be an event
+ var obj = document.createEvent('HTMLEvents');
+ obj.preventDefault = function() { return 'boo'; };
+ assertEquals('boo', obj.preventDefault());
+
+ // similarly for nodes
+ var obj = document.createElement('span');
+ obj.blur = function() { return 'boo'; };
+ assertEquals('boo', obj.blur());
+
+ pass('testExpandoOverride');
+ });
+</script>
+
<p id="testEditabilityInNodeLists" class="testcontainer">
editability in node lists<br>
</p>
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