數組對象添加屬性

如何給一個數組對象的每一項新增一個屬性 如：isSelected:true??

let newArr = arr.map(v=>{
      return {...v,isSelected:true}
})

let array = [{name: 'lili'}, {name:'petrel'}]
Array.from(array, item => item.isSelected = false)
console.log(array);

數組對象A,數組對象B，A中item.id === B中的item.id的對象新增屬性isSelected：false,否則新增屬性isSelected:true

const A=[{id: 1},{id:2}, {id: 4}];
const B=[{id: 1}, {id:2}, {id:3}];
const result = A.map(item => {
  
  return {
    ...item, 
    isSelected: B.filter(i=>{
      return item.id === i.id
    }).length > 0
  }
})
console.log(result)