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no-json-stringify-error

Avoid generic JSON serialization that can omit native Error details.

noJsonStringifyError Rule source Tests Catalog JSON

Why

Native Error details are non-enumerable, so generic JSON serialization discards diagnostic information.

Fix

Serialize explicit error fields or use an error-aware serializer.

Examples

Before — flagged A computed prototype name remains ordinary serialized data

src/error.js

JSON.stringify({
  error: new Error("lost"),
  ["__proto__"]: {
    toJSON() {
      return { message: "kept" };
    },
  },
});

After — preferred A literal prototype hook owns the payload serializer contract

src/error.js

JSON.stringify({
  error: new Error("lost"),
  __proto__: {
    toJSON() {
      return { message: "kept" };
    },
  },
});

Before — flagged A later write does not change an already constructed native Error

src/error.js

const value = new Error("lost");
Error = class Other {
  message = "kept";
};
JSON.stringify(value);

After — preferred A replaced constructor does not prove a native Error

src/error.js

Error = class Other {
  message = "kept";
};
const value = new Error();
JSON.stringify(value);

Before — flagged Keep native binding provenance

src/error.ts

function probe() {
  try {
    throw { id: 1 };
  } catch (err) {
    if (err instanceof Error) return err.message;
    {
      const err = new Error("lost");
      return JSON.stringify(err);
    }
  }
}
console.log(probe());

After — preferred Keep native binding provenance

src/error.ts

function probe() {
  try {
    throw { id: 1 };
  } catch (err) {
    if (err instanceof Error) return err.message;
    return JSON.stringify(err);
  }
}
console.log(probe());

Before — flagged Do not stringify an Error object

src/report.ts

try {
  f();
} catch (err) {
  JSON.stringify({ error: err });
}

After — preferred Narrow an unknown catch value before selecting fields

src/report.ts

try {
  f();
} catch (err) {
  JSON.stringify({ error: err instanceof Error ? err.message : String(err) });
}

Before — flagged A noncallable toJSON does not replace native serialization

src/error.js

JSON.stringify({ error: new Error("lost"), toJSON: 42 });

After — preferred An explicit callable toJSON owns its serialization contract

src/error.js

JSON.stringify({
  error: new Error("lost"),
  toJSON() {
    return { message: "kept" };
  },
});

Before — flagged A later write does not change an earlier native serialization

src/error.js

const result = JSON.stringify(new Error("lost"));
JSON.stringify = (value) => "kept:" + value.message;

After — preferred A replaced serializer owns its error-field contract

src/error.js

JSON.stringify = (value) => "kept:" + value.message;
JSON.stringify(new Error("lost"));

Before — flagged Serializing the whole Error still loses its native details

src/error.js

const error = new Error("lost", { cause: "kept" });
JSON.stringify(error);

After — preferred Native Error cause can be a string value

src/error.js

const error = new Error("lost", { cause: "kept" });
JSON.stringify(error.cause);

Before — flagged A constant computed serializer still loses native Error details

src/error.js

const key = "stringify";
JSON[key](new Error("lost"));

After — preferred A constant message field selects the explicit string escape hatch

src/error.js

const key = "message";
const error = new Error("lost");
JSON.stringify(error[key]);