# On/Off
### on / off
Adds or removes a listener for a specific event on a given layer.
```
// Adds a listener
mapInstance.on(type, layerId, listener);
// Removes a listener
mapInstance.off(type, layerId, listener);
```
#### Parameter
| Parameter | Description | Type |
| ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------- |
| type | specifies which event to listen to. | String |
| *Supported types:* |
"mouseup", "mousedown", "click", "dblclick", "mousemove", "mouseenter", "mouseleave, "mouseover", "mouseout", "contextmenu", "touchstart", touchend" or "touchcancel". "mouseenter" and "mouseover" events are triggered when the cursor enters a visible portion of the specified layer or map canvas from outside and vice versa for "mouseleave" and "mouseout".
| |
| layerId (Optional) | ID of a style layer. Only layer that matches the given parameter will trigger the event listener. | String |
| listener | A callback function that detects the event and triggers further procedures. | Function |
#### Example(Javascript + HTML)
```javascript
Map Event
```
---
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