How `satisfies` works

type WithId = {
     id: string
}

interface ColorWithId extends WithId {
     color?: string
}

// Declaring myColor1 with ColorWithId interface
const myColor1:ColorWithId = { id: 'a', color: 'red' }

myColor1.color.substring(0, 1)
//        ^ TypeError: 'myColor1.color' is possibly 'undefined'.
// To fix this, we need to apply optional chaining: `myColor1.color?.substring(0, 1)`
// But this doesn't make sense because it's obvious that there is a color property with the value 'red'!        

// How about using `as`?
const myColor2 = { id: 'a', color: 'red' } as ColorWithId

myColor2.color.substring(0, 1)
//        ^ TypeError: 'myColor1.color' is possibly 'undefined'.
// The same as above. You need the optional chaining.

// ***** How about using `satisfies`? ******
const myColor3 = { id: 'a', color: 'red' } satisfies ColorWithId

myColor3.color.substring(0, 1) // no TypeError! Because the value "satisfies" the type.

// Does `satisfies` still check the type correctly??
const myColor4 = { id: 'a', colors: 'red' } satisfies ColorWithId
//                             ^ TypeError: 'colors' does not exist in type 'ColorWithId'
// Yes, it does.