javascript - 如何根据前一个元素更新下一个元素值

Question

我有以下示例数组

let myArray = [
  {name: "Sam", status: 'not_started', progress: 'start'},
  {name: "Sara", status: 'not_started', progress: 'start'},
  {name: "John", status: 'not_started', progress: 'start'},
  {name: "Eric", status: 'not_started', progress: 'start'}
]

如果所有元素的状态都是:“not_started”，那么我想将第一个元素的进度更新为“start”，其余元素更新为“lock”。所以数组看起来像这样:

let myArray = [
  {name: "Sam", status: 'not_started', progress: 'start'},
  {name: "Sara", status: 'not_started', progress: 'lock'},
  {name: "John", status: 'not_started', progress: 'lock'},
  {name: "Eric", status: 'not_started', progress: 'lock'}
]

如果第一个元素的状态为“已完成”，那么第二个元素的状态为“开始”，其余元素的状态为“锁定”，如下所示

let myArray = [
  {name: "Sam", status: 'completed', progress: 'completed'},
  {name: "Sara", status: 'not_started', progress: 'start'},
  {name: "John", status: 'not_started', progress: 'lock'},
  {name: "Eric", status: 'not_started', progress: 'lock'}
]

此外，如果前两个“已完成”，那么它会如下所示

let myArray = [
  {name: "Sam", status: 'completed', progress: 'completed'},
  {name: "Sara", status: 'completed', progress: 'completed'},
  {name: "John", status: 'not_started', progress: 'start'},
  {name: "Eric", status: 'not_started', progress: 'lock'}
]

我尝试映射 myArray 并创建状态和进度值的数组，并根据状态progress: array[status]获取进度值，但这不会更新进度:'lock' 正确，因为 'not_started' 可以有进度:'start' 或 'lock'

显然我需要根据前一个的值更新下一个，但我还没有得到这一点。

有谁知道我怎样才能实现这个目标？

谢谢

Answer 1

您可以使用 map() 方法，并且在第一次出现 not_started 状态时，您可以将 this.started 设置为 true 并基于此将进度更改为锁定。

let myArray = [
  {name: "Sam", status: 'completed', progress: 'start'},
  {name: "Sara", status: 'not_started', progress: 'start'},
  {name: "John", status: 'not_started', progress: 'start'},
  {name: "Eric", status: 'not_started', progress: 'start'}
]
  
const result = myArray.map(function(e) {
  if(e.status == 'completed') return {...e, progress: 'completed'}
  if (this.started) return { ...e, progress: 'lock'}
  if (e.status == 'not_started') this.started = true;
  return { ...e};
}, {});

console.log(result)