js关于数组合并的问题

Question

`

list1 = [{id:1,name:'a'},{id:2,name:'b'}],
list2 = [{id:1,name:'aa'},{id:2,name:'bb'},{id:3,name:'cc'}]

`

比较两个数组，怎么把list2里id为3对象push到list1里(list1里不存在的对象)

Answer 1

const resule = [...list1, ...list2.filter(item => !list1.some(r => r.id===item.id))]

Answer 2

解构赋值即可

console.log( Object.values({...list2,...list1}))

Answer 3

function mergeList(source, target) {
    var ids = target.reduce((res, item) => (res.add(item.id), res), new Set)
    return target.concat( source.filter(item => !ids.has(item.id)) )
}

mergeList(list2, list1)