如何在 Typescript/Javascript 中獲取兩個對象數組之間的差異

Question

我有兩個對象數組，例如：

[{id: "1", name: "item1", checked: true}, {id: "2", name: "item2", checked: true}, {id: "3", name: "item3", checked: true}]

和

[{id: "1", name: "item1", checked: true}, {id: "2", name: "item2", checked: true}, {id: "3", name: "item3", checked: false}]

第一個數組保存默認狀態，第二個保存當前狀態。 我想過濾掉“檢查”更改的對象。 預期的結果是

[{id: "3", name: "item3", checked: false}]

我嘗試使用 loadash differentBy，但它返回空數組：

const diff=_.differenceBy(array1, array2, "checked")

任何人都可以幫忙嗎？ 謝謝。

Answer 1

如果數組中的項目由 keyToCompare 比較並由它的標識符標識（在您的情況下checked和id ），您可以使用這樣的方法。

const differenceBy = (arr1, arr2, keyToCompare, identifier) => {
    const diff = []
    arr1.forEach(arr => {
        const arr2Item = arr2.find(i => i[identifier] === arr[identifier])
        if(arr[keyToCompare] !== arr2Item[keyToCompare]) {
            diff.push(arr2Item)
        }
    })

    return diff
}

例子：

 const arr1 = [{id: "1", name: "item1", checked: true}, {id: "2", name: "item2", checked: true}, {id: "3", name: "item3", checked: true}] const arr2 = [{id: "1", name: "item1", checked: true}, {id: "2", name: "item2", checked: true}, {id: "3", name: "item3", checked: false}] const differenceBy = (arr1, arr2, keyToCompare, identifier) => { const diff = [] arr1.forEach(arr => { const arr2Item = arr2.find(i => i[identifier] === arr[identifier]) if(arr[keyToCompare] !== arr2Item[keyToCompare]) { diff.push(arr2Item) } }) return diff } console.log(differenceBy(arr1, arr2, 'checked', 'id'))

Answer 2

一個非常緊湊的解決方案-但是 O(n^2)- 帶有_.differenceWith ：

const xs = [
  {id: "1", name: "item1", checked: true}, 
  {id: "2", name: "item2", checked: true}, 
  {id: "3", name: "item3", checked: true}
]

const ys = [
  {id: "1", name: "item1", checked: true}, 
  {id: "2", name: "item2", checked: true}, 
  {id: "3", name: "item3", checked: false}
]

const zs = _.differenceWith(xs, ys, _.isEqual)
// [{ id: "3", name: "item3", checked: true }]

有點冗長，但這個是 O(n)：

const xsById = _.keyBy(xs, x => x.id)
const zs = ys.filter(y => xsById[y.id]?.checked !== y.checked)

Answer 3

我想你可以使用類似的東西

function compareArrays(arr1, arr2, keyCompared) {
    let d = []
    arr1.forEach((e,i)=>{
    if(e[keyCompared] !== arr2[i][keyCompared])
        d.push(e)
    })
    return d
}

例子：

 let array1 = [{id: "1", name: "item1", checked: true}, {id: "2", name: "item2", checked: true}, {id: "3", name: "item3", checked: true}] let array2 = [{id: "1", name: "item1", checked: true}, {id: "2", name: "item2", checked: true}, {id: "3", name: "item3", checked: false}] function compareArrays(arr1, arr2, keyCompared) { let d = [] arr1.forEach((e,i)=>{ if(e[keyCompared] !== arr2[i][keyCompared]) d.push(e) }) return d } console.log(compareArrays(array1,array2,'checked'))