템플릿 리터럴 타입 함정

type EventName = "click" | "focus" | "blur";
type Handler = `on${Capitalize<EventName>}`;

const handlers: Record<Handler, () => void> = {
    onClick: () => console.log("clicked"),
    onFocus: () => console.log("focused"),
    onBlur: () => console.log("blurred")
};

function addHandler(name: string, fn: () => void) {
    handlers[name] = fn;
}

addHandler("onScroll", () => console.log("scrolled"));