# AIMessageChunk

> **Class** in `@langchain/core`

📖 [View in docs](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk)

Represents a chunk of an AI message, which can be concatenated with
other AI message chunks.

## Signature

```javascript
class AIMessageChunk
```

## Extends

- `BaseMessageChunk<TStructure, "ai">`

## Implements

- `AIMessage<TStructure>`
- `AIMessageChunkFields<TStructure>`

## Constructors

- [`constructor()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/constructor)

## Properties

- `additional_kwargs`
- `content`
- `id`
- `invalid_tool_calls`
- `lc_kwargs`
- `lc_namespace`
- `lc_serializable`
- `name`
- `response_metadata`
- `tool_call_chunks`
- `tool_calls`
- `type`
- `usage_metadata`
- `_printableFields`
- `[toStringTag]`
- `contentBlocks`
- `lc_aliases`
- `lc_attributes`
- `lc_id`
- `lc_secrets`
- `lc_serializable_keys`
- `text`

## Methods

- [`_getType()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/_getType)
- [`_updateId()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/_updateId)
- [`concat()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/concat)
- [`getType()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/getType)
- [`toDict()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/toDict)
- [`toFormattedString()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/toFormattedString)
- [`toJSON()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/toJSON)
- [`toJSONNotImplemented()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/toJSONNotImplemented)
- [`isInstance()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/isInstance)
- [`lc_name()`](https://reference.langchain.com/javascript/langchain-core/messages/AIMessageChunk/lc_name)

---

[View source on GitHub](https://github.com/langchain-ai/langchainjs/blob/2a5713dfbc5987fb1dcf85cd1de9379816688927/libs/langchain-core/src/messages/ai.ts#L272)