diff --git a/samples/javascript/apidocs/ee-string-index.js b/samples/javascript/apidocs/ee-string-index.js
index e80cb644b..212b2adde 100644
--- a/samples/javascript/apidocs/ee-string-index.js
+++ b/samples/javascript/apidocs/ee-string-index.js
@@ -18,4 +18,7 @@
 print(ee.String('abc123').index(''));  // 0
 print(ee.String('abc123').index('c1'));  // 2
 print(ee.String('abc123').index('ZZ'));  // -1
+
+// index is case-sensitive.
+print(ee.String('abc123').index('BC'));  // -1
 // [END earthengine__apidocs__ee_string_index]
diff --git a/samples/python/apidocs/ee_string_index.py b/samples/python/apidocs/ee_string_index.py
index 3a43e93c3..d09431ac3 100644
--- a/samples/python/apidocs/ee_string_index.py
+++ b/samples/python/apidocs/ee_string_index.py
@@ -16,4 +16,7 @@
 print(ee.String('abc123').index('').getInfo())  # 0
 print(ee.String('abc123').index('c1').getInfo())  # 2
 print(ee.String('abc123').index('ZZ').getInfo())  # -1
+
+# index is case-sensitive.
+print(ee.String('abc123').index('BC').getInfo())  # -1
 # [END earthengine__apidocs__ee_string_index]