Merge pull request 'Implement optional chaining' (#1889) from FranklinDM/UXP-contrib:work_js-optional-chaining into master

Reviewed-on: https://repo.palemoon.org/MoonchildProductions/UXP/pulls/1889

1 files changed, 24 insertions, 0 deletions

diff --git a/js/src/tests/test262/language/optional-chaining/short-circuiting.js b/js/src/tests/test262/language/optional-chaining/short-circuiting.js
new file mode 100644
index 0000000000..74295cb1ee
--- /dev/null
+++ b/js/src/tests/test262/language/optional-chaining/short-circuiting.js
@@ -0,0 +1,24 @@
+// Copyright 2019 Google, Inc.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: prod-OptionalExpression
+description: >
+  demonstrate syntax-based short-circuiting.
+info: |
+  If the expression on the LHS of ?. evaluates to null/undefined, the RHS is
+  not evaluated
+features: [optional-chaining]
+---*/
+
+const a = undefined;
+let x = 1;
+
+a?.[++x] // short-circuiting.
+a?.b.c(++x).d; // long short-circuiting.
+
+undefined?.[++x] // short-circuiting.
+undefined?.b.c(++x).d; // long short-circuiting.
+
+assert.sameValue(1, x);
+
+reportCompare(0, 0);