# Reactions & Triggers: When

> What can start a reaction.

Glider documentation · Logic · Web page: https://cgglider.com/docs/reactions/events/

Sections of this page: [The model](https://cgglider.com/docs/reactions.md) · [When](https://cgglider.com/docs/reactions/events.md) · [Conditions](https://cgglider.com/docs/reactions/conditions.md) · [Then](https://cgglider.com/docs/reactions/actions.md) · [Chaining, delays & guards](https://cgglider.com/docs/reactions/chaining.md)

| Kind | Fires when |
| --- | --- |
| onTake | The page (or graphic) is taken to air. |
| onTakeOut | It is taken off air. |
| onEvent | A named event is emitted — by a button, another reaction, or the HTTP event endpoint. |
| onChange | A store path changes at all. |
| onCompare | A store path satisfies a comparison: eq, ne, lt, lte, gt, gte, in, not-in, contains. |
| onClipEnd | A named clip finishes. |

Clip triggers in the timeline offer a different list, because they are attached to a component: onData, onClick, onDoubleClick, onMouseEnter, onMouseLeave, onMount, and the three clip-lifecycle events onClipStart, onClipEnd, onClipLoop.