如何在 JavaScript 中组合具有相同元素的对象？

Question

I want to combine same key element in below object and new array as output.

    const items = [
    {status:'all',task:'AA'},
    {status:'all',task:'BB'},
    {status:'working',task:'XX'},
    {status:'working',task:'YY'},
    {status:'complete',task:'ZZ'},
]

In items, I want to combine same status and make new array like below.

    const newItems = [
    {status:'all',task:['AA','BB']},
    {status:'working',task:['XX','YY']},
    {status:'complete',task:['ZZ']},
]

So I tried to make code below.

    let baseItems = items
const newItems = baseItems.map((e)=>{
    const newBaseItems = baseItems.filter((v)=>v.status === e.status)
    newBaseItems.map((e)=>{
        return {
            status:e.status,
            task:e.task
        }
    })        
})
console.log(newItems)

but out was like [undefined,undefined,,,,] Does anyone teach me, please?

Answer 1

I don't think a nested loop is the right approach here. Iterate just once , into an object indexed by status . On each iteration, create a { status, task: [] } on the object if it doesn't exist yet, then push to the task array:

 const items = [ {status:'all',task:'AA'}, {status:'all',task:'BB'}, {status:'working',task:'XX'}, {status:'working',task:'YY'}, {status:'complete',task:'ZZ'}, ]; const itemsByStatus = {}; for (const { status, task } of items) { itemsByStatus[status]??= { status, task: [] }; itemsByStatus[status].task.push(task); } console.log(Object.values(itemsByStatus));