--- layout: api title: "v2.1.2 JavaScript Library: Events methods" categories: api version: v2.1.2 permalink: /api/v2.1.2/l-events ---

## Events methods

A set of methods shared between event-powered classes (like Map). Generally, events allow you to execute some function when something happens with an object (e.g. the user clicks on the map, causing the map `'fire'` event).

### Example

    map.on('click', function(e) {
    	alert(e.latlng);
    });

Leaflet deals with event listeners by reference, so if you want to add a listener and then remove it, define it as a function:

    function onClick(e) { ... }

    map.on('click', onClick);
    map.off('click', onClick);

### Methods

Method | Returns | Description
--- | --- | ---
`addEventListener( <String> type, <Function> fn, <Object> context? )` | `this` | Adds a listener function (`fn`) to a particular event type of the object. You can optionally specify the context of the listener (object the `this` keyword will point to). You can also pass several space-separated types (e.g. `'click dblclick'`).
`addOneTimeEventListener( <String> type, <Function> fn, <Object> context? )` | `this` | The same as above except the listener will only get fired once and then removed.
`addEventListener( <Object> eventMap, <Object> context? )` | `this` | Adds a set of type/listener pairs, e.g. `{click: onClick, mousemove: onMouseMove}`
`removeEventListener( <String> type, <Function> fn?, <Object> context? )` | `this` | Removes a previously added listener function. If no function is specified, it will remove all the listeners of that particular event from the object.
`removeEventListener( <Object> eventMap, <Object> context? )` | `this` | Removes a set of type/listener pairs.
`removeEventListener()` | `this` | Removes all listeners. An alias to `clearAllEventListeners` when you use it without arguments.
`hasEventListeners( <String> type )` | `Boolean` | Returns `true` if a particular event type has some listeners attached to it.
`fireEvent( <String> type, <Object> data? )` | `this` | Fires an event of the specified type. You can optionally provide an data object — the first argument of the listener function will contain its properties.
`clearAllEventListeners()` | `this` | Removes all listeners to all events on the object.
`on( … )` | `this` | Alias to `addEventListener`.
`once( … )` | `this` | Alias to `addOneTimeEventListener`.
`off( … )` | `this` | Alias to `removeEventListener`.
`fire( … )` | `this` | Alias to `fireEvent`.