配列・オブジェクトからリテラル型を生成する

const variants = ['primary', 'secondary', 'danger', 'warning', 'safe'] as const

type Variant = typeof variants[number] // "primary" | "secondary" | "danger" | "warning" | "safe"

const buttons = {
    variant: 'primary',
    text: 'hello',
    size: 'sm'
} as const

type ButtonProps = typeof buttons[keyof typeof buttons] // "primary" | "hello" | "sm"

type ButtonProps = keyof typeof buttons // "variant" | "text" | "size"