Event Router

An app emits three kinds of event, modelled as a discriminated union on kind. Write describeEvents(events) that turns each event into one line of text:

click: click at (X, Y)
key: key K, or shortcut Ctrl+K when ctrl is true
scroll: scroll down N for a positive delta, scroll up N for a negative one (N is always positive)

Handle every kind in a switch, and finish with a never check so adding a fourth kind later becomes a compile error instead of a silent bug.

Examples

describeEvents([{ kind: "click", x: 10, y: 20 }, { kind: "key", key: "s", ctrl: true }, { kind: "scroll", delta: -40 }])

→ ["click at (10, 20)", "shortcut Ctrl+s", "scroll up 40"]

describeEvents([{ kind: "key", key: "Enter", ctrl: false }, { kind: "scroll", delta: 15 }])

→ ["key Enter", "scroll down 15"]

project.ts

TYPESCRIPT

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Tests

0 of 3 passing

•
one of each
describeEvents([{ kind: "click", x: 10, y: 20 }, { kind: "key", key: "s", ctrl: true }, { kind: "scroll", delta: -40 }])
expected ["click at (10, 20)", "shortcut Ctrl+s", "scroll up 40"]
•
plain key and scroll down
describeEvents([{ kind: "key", key: "Enter", ctrl: false }, { kind: "scroll", delta: 15 }])
expected ["key Enter", "scroll down 15"]
•
no events
describeEvents([])
expected []

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Pass all 3 tests to claim it.