LibJS: Fix that non-double numbers from JSON were truncated to i32

2 files changed, 26 insertions, 3 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/JSONObject.cpp b/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
index 1bf5b28d53..349a5e43a9 100644
--- a/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
@@ -416,10 +416,10 @@ Value JSONObject::parse_json_value(VM& vm, JsonValue const& value)
         return Value(parse_json_array(vm, value.as_array()));
     if (value.is_null())
         return js_null();
-    if (value.is_double())
-        return Value(value.as_double());
+    if (value.is_i32())
+        return Value(value.as_i32());
     if (value.is_number())
-        return Value(value.to_i32(0));
+        return Value(value.to_double(0));
     if (value.is_string())
         return js_string(vm, value.to_string());
     if (value.is_bool())
diff --git a/Userland/Libraries/LibJS/Tests/builtins/JSON/JSON.parse.js b/Userland/Libraries/LibJS/Tests/builtins/JSON/JSON.parse.js
index ff4d4bd30e..c42dbafa57 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/JSON/JSON.parse.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/JSON/JSON.parse.js
@@ -51,3 +51,26 @@ test("negative zero", () => {
 test("long decimal parse", () => {
     expect(JSON.parse("1644452550.6489999294281")).toEqual(1644452550.6489999294281);
 });
+
+test("does not truncate large integers", () => {
+    expect(JSON.parse("1234567890123")).toEqual(1234567890123);
+    expect(JSON.parse("4294967295")).toEqual(4294967295);
+    expect(JSON.parse("4294967296")).toEqual(4294967296);
+    expect(JSON.parse("4294967297")).toEqual(4294967297);
+    expect(JSON.parse("4294967298")).toEqual(4294967298);
+
+    expect(JSON.parse("2147483647")).toEqual(2147483647);
+    expect(JSON.parse("2147483648")).toEqual(2147483648);
+    expect(JSON.parse("2147483649")).toEqual(2147483649);
+    expect(JSON.parse("2147483650")).toEqual(2147483650);
+
+    expect(JSON.parse("9007199254740991")).toEqual(9007199254740991);
+    expect(JSON.parse("9007199254740992")).toEqual(9007199254740992);
+    expect(JSON.parse("9007199254740993")).toEqual(9007199254740993);
+    expect(JSON.parse("9007199254740994")).toEqual(9007199254740994);
+    expect(JSON.parse("9008199254740994")).toEqual(9008199254740994);
+
+    expect(JSON.parse("18446744073709551615")).toEqual(18446744073709551615);
+    expect(JSON.parse("18446744073709551616")).toEqual(18446744073709551616);
+    expect(JSON.parse("18446744073709551617")).toEqual(18446744073709551617);
+});