diff --git a/tests/baselines/reference/jsContainerMergeJsContainer.symbols b/tests/baselines/reference/jsContainerMergeJsContainer.symbols
new file mode 100644
index 00000000000..1f4728d50de
--- /dev/null
+++ b/tests/baselines/reference/jsContainerMergeJsContainer.symbols
@@ -0,0 +1,18 @@
+=== tests/cases/conformance/salsa/a.js ===
+// #24131
+const a = {};
+>a : Symbol(a, Decl(a.js, 1, 5), Decl(a.js, 1, 13), Decl(b.js, 0, 0))
+
+a.d = function() {};
+>a.d : Symbol(d, Decl(a.js, 1, 13), Decl(b.js, 0, 2))
+>a : Symbol(a, Decl(a.js, 1, 5), Decl(a.js, 1, 13), Decl(b.js, 0, 0))
+>d : Symbol(d, Decl(a.js, 1, 13), Decl(b.js, 0, 2))
+
+=== tests/cases/conformance/salsa/b.js ===
+a.d.prototype = {};
+>a.d.prototype : Symbol(d.prototype, Decl(b.js, 0, 0))
+>a.d : Symbol(d, Decl(a.js, 1, 13), Decl(b.js, 0, 2))
+>a : Symbol(a, Decl(a.js, 1, 5), Decl(a.js, 1, 13), Decl(b.js, 0, 0))
+>d : Symbol(d, Decl(a.js, 1, 13), Decl(b.js, 0, 2))
+>prototype : Symbol(d.prototype, Decl(b.js, 0, 0))
+
diff --git a/tests/baselines/reference/jsContainerMergeJsContainer.types b/tests/baselines/reference/jsContainerMergeJsContainer.types
new file mode 100644
index 00000000000..fa5c74f5b05
--- /dev/null
+++ b/tests/baselines/reference/jsContainerMergeJsContainer.types
@@ -0,0 +1,23 @@
+=== tests/cases/conformance/salsa/a.js ===
+// #24131
+const a = {};
+>a : { [x: string]: any; d: typeof d; }
+>{} : { [x: string]: any; d: typeof d; }
+
+a.d = function() {};
+>a.d = function() {} : typeof d
+>a.d : typeof d
+>a : { [x: string]: any; d: typeof d; }
+>d : typeof d
+>function() {} : typeof d
+
+=== tests/cases/conformance/salsa/b.js ===
+a.d.prototype = {};
+>a.d.prototype = {} : { [x: string]: any; }
+>a.d.prototype : { [x: string]: any; }
+>a.d : typeof d
+>a : { [x: string]: any; d: typeof d; }
+>d : typeof d
+>prototype : { [x: string]: any; }
+>{} : { [x: string]: any; }
+
diff --git a/tests/cases/conformance/salsa/jsContainerMergeJsContainer.ts b/tests/cases/conformance/salsa/jsContainerMergeJsContainer.ts
new file mode 100644
index 00000000000..3d6cbb35b75
--- /dev/null
+++ b/tests/cases/conformance/salsa/jsContainerMergeJsContainer.ts
@@ -0,0 +1,10 @@
+// @noEmit: true
+// @allowJs: true
+// @checkJs: true
+
+// #24131
+// @Filename: a.js
+const a = {};
+a.d = function() {};
+// @Filename: b.js
+a.d.prototype = {};