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Marina
Asked:2020-04-11 03:36:34 +0000 UTC2020-04-11 03:36:34 +0000 UTC

不要将非唯一对象添加到数组

  • 772

有一个水果对象数组，可以将对象添加到所选数组中。

let fruits = [{Id: 1, Name: 'Apple'}, {Id: 2, Name: 'Pear'},
{ Id: 3, Name: 'Orange'}, { Id: 4, Name: 'Plum'}, { Id: 5, Name: 'Cherry'}];

let selected = [{Id: 3, Name: 'Orange'}];

如果那里已经有类似的对象，如何防止将来自水果的对象添加到选定对象。例如，让 Id = 3 的对象不再添加到 selected 中，但其余的都添加？IE支持很重要。

javascript

2 个回答

  1. Best Answer

    let fruits = [
  { Id: 1, Name: 'Apple' }, 
  { Id: 2, Name: 'Pear' },
  { Id: 3, Name: 'Orange' }, 
  { Id: 4, Name: 'Plum' }, 
  { Id: 5, Name: 'Cherry' }
];
let selected = [{Id: 3, Name: 'Orange'}];

function addUniqueIds(src, dst) {
  var lookup = {};
  for (var i = 0; i < dst.length; i++) {
    lookup[dst[i].Id] = true;
  }  
  for (var i = 0; i < src.length; i++) {
    if (!lookup[src[i].Id]) {
      lookup[src[i].Id] = true;
      dst.push(src[i]);
    }
  }
}

addUniqueIds(fruits, selected);
console.log(selected.length, selected);

    • 1

  2. 如果突然有人对ie不那么重要的支持，那么这里：

    1.如果字段的顺序没有改变

    const fruits = [{Id: 1, Name: 'Apple'}, {Id: 2, Name: 'Pear'}, { Id: 3, Name: 'Orange'}, { Id: 4, Name: 'Plum'}, { Id: 5, Name: 'Cherry'}];

const selected = [{Id: 3, Name: 'Orange'}];

const newSelect = selected.map((item) => JSON.stringify(item));

const result = fruits.reduce((acc, item) => {
  if(!newSelect.includes(JSON.stringify(item))) {
    return acc.concat(item);
  }
  return acc;
}, selected)

console.log(result)

    2.如果字段顺序改变（备注来自@n3r0bi0m4n）

    const fruits = [{Id: 1, Name: 'Apple'}, {Id: 2, Name: 'Pear'}, { Id: 3, Name: 'Orange'}, { Id: 4, Name: 'Plum'}, { Id: 5, Name: 'Cherry'}];

const selected = [{Name: 'Orange', Id: 3}, {Name: 'Pear', Id: 2}];

const newSelect = selected.map((item) => (item.Id));

const result = fruits.reduce((acc, item) => {
  if(!newSelect.includes(item.Id)) {
    return acc.concat(item);
  }
  return acc;
}, selected)

console.log(result)

    • 1

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