Question

以下是我当前设置的简化版本。

运行此代码时，您会注意到修改changes数组也会操纵原始referrals数组。这是因为我push changes在地图函数中的changes数组？如何在不修改referrals数组的情况下修改var referrals = [ { id: 1, name: 'John', change: true }, { id: 2, name: 'Sally', change: false }, { id: 3, name: 'Kim', change: true } ]; var changes = []; var process = referrals.map(function(referral) { return new Promise(function(resolve, reject) { if (referral.change) { changes.push(referral); } resolve(); }); }); Promise.all(process).then(function() { console.log('referrals before:', referrals); changes = changes.map(function(change) { change.change_id = change.id; delete change.id; return change; }); console.log('changes:', changes); console.log('referrals after:', referrals); });数组？

＆＃13;

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＆＃13;

Answer 1

您只需要创建内部对象的深层副本，您可以使用lodash deepClone或spread operator来完成。

类似的东西：

var referrals = [
{
  id: 1,
  name: 'John',
  change: true
},
{
  id: 2,
  name: 'Sally',
  change: false
},
{
  id: 3,
  name: 'Kim',
  change: true
}
];

var changes = [];

var process = referrals.map(function(referral) {
  return new Promise(function(resolve, reject) {
    if (referral.change) {
      changes.push({...referral}); // You will create a copy here.
    }
    resolve();
  });
});

Promise.all(process).then(function() {
  console.log('referrals before:', referrals);
  changes = changes.map(function(change) {
  change.change_id = change.id;
  delete change.id;
  return change;
});

console.log('changes:', changes);
console.log('referrals after:', referrals);
});

Answer 2

感谢blex让我了解这里发生的事情。基本上当我将对象推送到一个新数组时，我正在推送整个引用，而不仅仅是一个副本。使用Object.assign克隆对象解决了我的问题。

以下是整个编辑供参考：

var referrals = [
  {
    id: 1,
    name: 'John',
    change: true
  },
  {
    id: 2,
    name: 'Sally',
    change: false
  },
  {
    id: 3,
    name: 'Kim',
    change: true
  }
];

var changes = [];

var process = referrals.map(function(referral) {
  new Promise(function(resolve, reject) {
    if (referral.change) {
      changes.push(Object.assign({}, referral));
    }
    resolve();
  });
});

Promise.all(process).then(function() {
  console.log('referrals before:', referrals);
  changes = changes.map(function(change) {
    change.change_id = change.id;
    delete change.id;
    return change;
  });

  console.log('changes:', changes);
  console.log('referrals after:', referrals);
});

推送到地图/承诺内的新数组

2 个答案: