求大佬告知如何实现联合类型？

interface Type1 { 
  a:Number 
} 
export interface Type2 { 
  b:string 
} 
type Type1OrType2=Type1|Type2 
  
let object1:Type1OrType2={a:100} 
let object2:Type1OrType2={b:'Type2'} 
console.log(object1.a.toString()) 
console.log(object2.b)