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new 6d77e2c null-conditional-operator: add bracket notation
6d77e2c is described below
commit 6d77e2c62d51a26eff0247a4dab4ec1c861c270b
Author: Josh Tynjala <[email protected]>
AuthorDate: Tue Oct 7 10:05:29 2025 -0700
null-conditional-operator: add bracket notation
---
features/as3/null-conditional-operator.md | 33 +++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/features/as3/null-conditional-operator.md
b/features/as3/null-conditional-operator.md
index b6bc601..6a81f02 100644
--- a/features/as3/null-conditional-operator.md
+++ b/features/as3/null-conditional-operator.md
@@ -48,6 +48,39 @@ var resolved:Object = obj?.a;
trace(resolved); // 123.4
```
+## Null conditional operator with bracket notation
+
+_Requires Apache Royale 0.9.13 or newer._
+
+The Royale compiler also supports a variation of the null conditional operator
using bracket notation, to request a property using a string value. This can be
useful for accessing properties with names that are known at run-time, but not
at compile-time.
+
+### Code example (bracket notation)
+
+Consider the following code that uses the `?.` operator with bracket notation
to access the field specified by a string on the condition that the object is
not nullish.
+
+```as3
+var obj:Object = null;
+var resolved:Object = obj?.["a"];
+trace(resolved); // null
+```
+
+If the expression `obj["a"]` were used instead of `obj?.["a"]`, then an
exception would be thrown instead.
+
+If the object is not nullish, then it works similarly to regular dynamic
access with bracket notation.
+
+```as3
+var obj:Object = {a: 123.4};
+var resolved:Object = obj?.["a"];
+trace(resolved); // 123.4
+```
+
+Alternatively, the brackets may contain any expression that results in a
string value, such as variables.
+
+```as3
+var name:String = "a";
+var resolved:Object = obj?.[name];
+```
+
## Limitations of the null conditional operator in Royale
Other ActionScript compilers, such as the one in the [Apache Flex
SDK](https://flex.apache.org/){:target='_blank'}, may not recognize the null
conditional operator. Attemping to pass ActionScript or MXML source code that
contains null conditional operators to another compiler may result in
compile-time errors. In other words, to write 100% portable ActionScript code
that works with any compiler, avoid using null conditional operator and any of
Royale's other [extensions to the ActionScri [...]
