on: Event handlers

In termr: Modern Reactive Terminal Applications with Data Workflows

Event handlers

Description

on() creates an event handler that can be passed to app() together with the widgets. It is equivalent to calling app$on().

Usage

on(type, selector = NULL, handler)

Arguments

type	Event type such as "button.pressed", "input.submitted", "key", "resize", "focus" or "mount". "*" matches any type.
selector	Optional selector (e.g. "#hello", ".danger", "Button") matched against the sender (for key and mouse events: the widget the event was sent to).
handler	⁠function(event, app)⁠.

Details

The handler runs when an event of the given type reaches the app and, if a selector is given, the widget that sent the event matches it.

Value

An object of class termr_handler.

Examples

on("button.pressed", "#hello", function(event, app) {
  app$query_one("#output")$update("Hello!")
})

termr documentation built on Oct. 21, 2026, 5:13 p.m.