如何使用javascript更新属性并获取数组对象中连续顺序具有属性值的结果

Question

我有对象数组list，参数rid和rorder被传递。

-> 1. 如果rid与列表中的id相同，则用rorder更新itemorder > 值。

-> 2.UpdatedList uList 属性 itemorder 如果存在相同的值，则递增该值，直到其连续顺序 (1,2, 3...n)

var rid = 23; var rvalue = 2
const list = [
  { id: 12, itemorder:null, place : 'IN' },
  { id: 24, itemorder: 1, place: 'MY' }, 
  { id: 23, itemorder: 4, place: 'AU' },
  { id: 44, itemorder: 3, place: 'SG' },
  { id: 54, itemorder: 2, place: 'CN' }, 
];

//updated List will be
const uList = [
  { id: 12, itemorder:null, place : 'IN' },
  { id: 24, itemorder: 1, place: 'MY' }, 
  { id: 23, itemorder: 2, place: 'AU' }, // updates since id and rid same // 2
  { id: 44, itemorder: 3, place: 'SG' }, // 4
  { id: 54, itemorder: 2, place: 'CN' }, // 3
];

// uList property itemorder has same value here `2`, increment until consecutive (1,2, 3...n).

Expected Output

[
  { id: 12, itemorder:null, place : 'IN' },
  { id: 24, itemorder: 1, place: 'MY' }, 
  { id: 23, itemorder: 2, place: 'AU' },
  { id: 44, itemorder: 4, place: 'SG' },
  { id: 54, itemorder: 3, place: 'CN' }, 
];

Tried 

var listChanged = list.map(e=> ({
  ...e,
  itemorder: e.id===rid ? rvalue : e.itemorder
}))

var result = listChanged.map(i => ({
  ...e,
  itemorder: (i.itemorder !== rvalue && i.itemorder > rvalue) ? (i.itemorder || 0)+1 : i.itemorder
}));

when passing var rid = 23; var rvalue = 1

Expected Output:

[
  { id: 12, itemorder:null, place : 'IN' },
  { id: 24, itemorder: 2, place: 'MY' }, // 1 becomes 2
  { id: 23, itemorder: 1, place: 'AU' }, // updates since both id and rid same
  { id: 44, itemorder: 4, place: 'SG' },//3 becomes 4
  { id: 54, itemorder: 3, place: 'CN' }, //2 becomes 3
]

no repeat values so increment, follows consecutive order (1,2,3..n)

Answer 1

var rid = 23; var rvalue = 2
const list = [
  { id: 12, itemorder: null, place: 'IN' },
  { id: 24, itemorder: 1, place: 'MY' },
  { id: 23, itemorder: 4, place: 'AU' },
  { id: 44, itemorder: 3, place: 'SG' },
  { id: 54, itemorder: 2, place: 'CN' },
];

let ridIdx = list.findIndex(x => x.id === rid)

orderedList = list.map((l,i) => {
    if(i === ridIdx) {
        return {
        ...l,
        itemorder: rvalue
        }
    }
    if(i > ridIdx) {
        return {
            ...l,
            itemorder: l.itemorder + 1
        }
    }
    return l
})

console.log(orderedList)

上面的代码应该可以工作。 到目前为止，根据我从您的问题中了解到的信息，我们执行以下步骤：

1. 在列表中查找给定rid的项目
2. 现在映射列表，并根据第1步找到的索引，默认返回，如果项目索引与上面的索引匹配，则将iteorder返回为右值，并通过增加现有的iteorder来返回如果项目索引大于找到的索引，则值加 1