Use an object instead of a sparse array, for IE 11 TP. Also, add a test.

paulmillr · Apr 10, 2015 · 1d80b06 · 1d80b06
1 parent 99a40ce
commit 1d80b06
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Showing 2 changed files with 10 additions and 3 deletions.
diff --git a/es6-shim.js b/es6-shim.js
@@ -1138,9 +1138,7 @@
     var assignHasPendingExceptions = Object.assign && Object.preventExtensions && (function () {
       // Firefox 37 still has "pending exception" logic in its Object.assign implementation,
       // which is 72% slower than our shim, and Firefox 40's native implementation.
-      /*jshint elision: true */
-      var thrower = Object.preventExtensions([,1]);
-      /*jshint elision: false */
+      var thrower = Object.preventExtensions({ 1: 2 });
       try {
         Object.assign(thrower, 'xy');
       } catch (e) {

diff --git a/test/object.js b/test/object.js
@@ -8,6 +8,7 @@ describe('Object', function () {
 
   var functionsHaveNames = (function foo() {}).name === 'foo';
   var ifFunctionsHaveNamesIt = functionsHaveNames ? it : xit;
+  var ifExtensionsPreventable = Object.preventExtensions ? it : xit;
 
   if (Object.getOwnPropertyNames) {
     describe('Object.getOwnPropertyNames()', function () {
@@ -202,6 +203,14 @@ describe('Object', function () {
       expect(Object.assign({ a: 1 }, undefined, { b: 2 })).to.eql({ a: 1, b: 2 });
       expect(Object.assign({ a: 1 }, { b: 2 }, null)).to.eql({ a: 1, b: 2 });
     });
+
+    ifExtensionsPreventable('does not have pending exceptions', function () {
+      // Firefox 37 still has "pending exception" logic in its Object.assign implementation,
+      // which is 72% slower than our shim, and Firefox 40's native implementation.
+      var thrower = Object.preventExtensions({ 1: 2 });
+      try { Object.assign(thrower, 'xy'); } catch (e) {}
+      expect(thrower).to.have.property(1, 2);
+    });
   });
 
   describe('Object.setPrototypeOf()', function () {