> For the complete documentation index, see [llms.txt](https://docs.heisenware.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.heisenware.com/app-builder/build-backend/functions/storage/circular-buffer.md).
# Circular buffer
The circular buffer class implements a fixed-size ring buffer structure where elements connect end-to-end. When the buffer reaches capacity, new items overwrite the oldest entries. Use this class for streaming data where only the most recent values matter, such as maintaining the last 100 data points for a live chart widget.
Data remains in memory only and does not persist to disk. This class requires an instance. The code class name is `CircularBuffer`.
### `create`
Creates a new circular buffer instance with a specified capacity.
#### Parameters
Input
Description
Type
capacity
The maximum number of items the buffer can hold. Default 100.
integer
#### Output
Returns the circular buffer instance.
#### Examples
```yaml
# capacity
10
```
### `pushBack`
Adds an item to the back of the buffer. If the buffer is full, the item at the front is overwritten.
#### Parameters
Input
Description
Type
value
The value or object to add.
any
#### Output
Returns nothing.
#### Examples
```yaml
# value
Another new item
```
### `pushFront`
Adds an item to the front of the buffer. If the buffer is full, the item at the back is overwritten.
#### Parameters
Input
Description
Type
value
The value or object to add.
any
#### Output
Returns nothing.
### `popFront`
Removes and returns the item from the front of the buffer.
#### Parameters
None.
#### Output
Returns the removed value or object.
### `popBack`
Removes and returns the item from the back of the buffer.
#### Parameters
None.
#### Output
Returns the removed value or object.
### `getBuffer`
Returns all items currently inside the buffer as a standard array, ordered from front to back.
#### Parameters
None.
#### Output
Returns an array containing all stored values.
### `getSize`
Returns the current number of items stored in the buffer.
#### Parameters
None.
#### Output
Returns the current item count as an integer.
### `getCapacity`
Returns the maximum number of items the buffer can hold.
#### Parameters
None.
#### Output
Returns the buffer capacity configuration as an integer.
### `clear`
Removes all contents and empties the buffer.
#### Parameters
None.
#### Output
Returns `true`.
### `delete`
Removes the circular buffer instance.
#### Parameters
None.
#### Output
Returns nothing.
{% hint style="danger" %}
#### Permanent data loss
Deleting removes the instance configuration. All buffered data is permanently lost.
{% endhint %}
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