deploy: 63c10a51fc

features/element_access.md

@@ -5,5 +5,19 @@ There are many ways elements in a JSON value can be accessed:
 - unchecked access via [`operator[]`](unchecked_access.md)
 - checked access via [`at`](checked_access.md)
 - access with default value via [`value`](default_value.md)
-- iterators
-- JSON pointers
+- [iterators](../iterators.md)
+- [JSON pointers](../json_pointer.md)
+
+Testing whether a key or index exists before accessing it is also possible, with
+[`contains`](../../api/basic_json/contains.md) or [`find`](../../api/basic_json/find.md) (which returns an iterator to
+the value, or `end()` if it is not found).
+
+```mermaid
+flowchart TD
+    A["accessing a value"] --> B{"must it exist?"}
+    B -->|"yes, missing is an error"| C["at() -- throws"]
+    B -->|"yes, but checking is my job"| D["operator[] -- unchecked"]
+    B -->|"no, a fallback is fine"| E["value() -- default value"]
+    A --> F{"just testing first?"}
+    F -->|"yes"| G["contains() / find()"]
+```