如何给一个数组对象的每一项新增一个属性 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);

数组对象A,数组对象B，A中item.id === B中的item.id的对象新增属性isSelected：false,否则新增属性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)