---
title: Judge
seo:
  title: Judge — TypeScript SDK
  description: Base class for building custom evaluation scorers. (TypeScript SDK)
description: Base class for building custom evaluation scorers.
---

Subclass `Judge` and implement the `score` method to create your own
evaluation logic.

```typescript
class ContainsAnswer extends Judge<BinaryResponse> {
  async score(data: Example): Promise<BinaryResponse> {
    const expected = (data.get("expected_output") as string).toLowerCase();
    const actual = (data.get("actual_output") as string).toLowerCase();
    return {
      value: actual.includes(expected),
      reason: actual.includes(expected) ? "Found" : "Not found",
    };
  }
}
```