> ## Documentation Index
> Fetch the complete documentation index at: https://orderly.network/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# useOrderbookStream

> Hook to stream formatted orderbook data with depth control and auto symbol switching.

`@orderly.network/hooks` provides `useOrderbookStream` to return formatted data of the orderbook, making it easy for the orderbook to be displayed on the UI. When the `symbol` parameter changes, the hook will automatically subscribe for the data of the new symbol, thus no additional handling is required.

* [Tech docs](/sdks/tech-doc/modules/orderly_network_hooks#useorderbookstream)

```typescript theme={null}
const [data, { onDepthChange, isLoading, onItemClick, depth, allDepths }] = useOrderbookStream(
  symbol,
  undefined,
  {
    level: 7,
    padding: false
  }
);
```

`useOrderbookStream` returns an array, where the first element is the formatted orderbook data and the second element is an `object` conatining some data regarding the orderbook status.

## Data structure

`[0]` The orderbook data format is as follows:

```json theme={null}
// Taking a data snapshot of PERP_ETH_USDC as an example
{
  "asks": [
    [2002.9, 0.0181, 0.0181]
    // ...
  ],
  "bids": [
    [2016.7, 0.0007, 0.0007]
    // ...
  ],
  "markPrice": 999,
  "middlePrice": 999
}
```

* The data in each of the asks/bids is (in order):
  * Price
  * Quantity
  * Aggregated quantity, which is the sum of the current row plus all preceding rows
* asks - List of ask order levels, sorted in ascending order
* bids - List of bid order levels, sorted in descending order

<Note>
  The default length of the orderbook is 10. This can be modified through the `level` parameter.
</Note>

## Depth

### allDepths

`allDepths` is an array containing all the different price tick granularities that the current symbol supports.

### onDepthChange

`onDepthChange` is a function that is used when a user changes the price tick granularity display of the orderbook. The hook will aggregate the orderbook levels according to this parameter when providing the orderbook data.