Update JSON.stringify type definition to handle function types

mattpocock · Mar 7, 2024 · 311c3f3 · 311c3f3
1 parent 3d460f3
commit 311c3f3
Show file tree

Hide file tree

Showing 2 changed files with 14 additions and 2 deletions.
diff --git a/src/entrypoints/json-stringify.d.ts b/src/entrypoints/json-stringify.d.ts
@@ -10,7 +10,9 @@ interface JSON {
     replacer?: (this: any, key: string, value: any) => any,
     space?: string | number,
   ): T extends {} | null
-    ? string
+    ? T extends () => void
+      ? undefined
+      : string
     : T extends undefined
     ? undefined
     : string | undefined;
@@ -25,7 +27,9 @@ interface JSON {
     replacer?: (number | string)[] | null,
     space?: string | number,
   ): T extends {} | null
-    ? string
+    ? T extends () => void
+      ? undefined
+      : string
     : T extends undefined
     ? undefined
     : string | undefined;

diff --git a/src/tests/json-stringify.ts b/src/tests/json-stringify.ts
@@ -25,6 +25,7 @@ doNotExecute(() => {
 
   type tests = [Expect<Equal<typeof result, string>>];
 });
+
 doNotExecute(() => {
   // create a something that is either an object or undefined
   let toBeStringified: {} | undefined = Math.random() > 0.5 ? {} : undefined;
@@ -33,6 +34,13 @@ doNotExecute(() => {
   type tests = [Expect<Equal<typeof result, string | undefined>>];
 });
 
+doNotExecute(() => {
+  // create a something that is a function
+  const result = JSON.stringify(function () {});
+
+  type tests = [Expect<Equal<typeof result, undefined>>];
+});
+
 doNotExecute(() => {
   // create a something that is of type any
   let toBeStringified: any;