# Class: eventHandler

## utils. eventHandler

#### new eventHandler()

### Methods

#### off(eventName [, handler])

  Remove an event handler

  ##### Parameters:

  Name | Type | Argument | Description
  --- | --- | --- | ---
  `eventName` | string |  | The name of the event to remove the handler for
  `handler` | function | <optional> | The handler associated with this event to be removed

  ##### Returns:

  Returns the object that 'off' is being called on.

  Type
    object

#### on(eventName, handler)

  Add an event handler

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `eventName` | string | The name of the event to listen to
  `handler` | function | The function to be called when the event is triggered

  ##### Returns:

  Returns the object that 'on' is being called on.

  Type
    object

#### one(eventName, handler)

  Add an event handler that will be removed automatically after being handled the first time

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `eventName` | string | The name of the event to listen to
  `handler` | function | The function to be called when the event is triggered

  ##### Returns:

  Returns the object that 'one' is being called on.

  Type
    object

#### trigger(eventName, eventParams)

  Trigger an event

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `eventName` | string | The name of the event to trigger
  `eventParams` | array | Parameters associated with the event

  ##### Returns:

  Returns the object that 'trigger' is being called on.

  Type
    object

  ##### Example

      annotManager.trigger('annotationChanged', [[annotation], 'modify']);

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