[typescript] the difference between exclamation mark and question mark in typescript

// Because of the interface B Inside name Defined as nullable value , But the actual situation is not empty ,
// Then we can pass on class It uses ！, Re emphasize name This is not null
!: Said no name Initial value

class A implemented B {
    
  name!: string
}

?: Express name Is an optional parameter , It means dispensable

interface B {
    
  name?: string
}