# TreeLoadStartDetail

> _Since v3.4.0_

Event detail emitted when lazy child loading starts for a node.

## Properties

| Property | Type | Description |
| -------- | ---- | ----------- |
| `key` | <code>string</code> | Stable key of the node whose children are being fetched |
| `row` | <code>T</code> | The parent row data |
| `depth` | <code>number</code> | Depth level of the parent node (0 = root) |