# ui.Map.onTileLoaded

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Registers a callback that's fired when a map tile has been loaded.

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Returns an ID which can be passed to unlisten() to unregister the callback.

| Usage | Returns |
|---|---|
| `Map.onTileLoaded(callback)` | String |

| Argument | Type | Details |
|---|---|---|
| this: `ui.map` | ui.Map | The ui.Map instance. |
| `callback` | Function | Called with an array of per layer values. Each value is the fraction of tiles still pending: a value of 0 means there are no more tiles to load for the layer. |