如果某些值匹配，如何替换数组的数据[重复]答案

【问题标题】：How to replace data of an array if some value match [duplicate]如果某些值匹配，如何替换数组的数据[重复]
【发布时间】：2021-06-08 21:31:22
【问题描述】：

我有这个数组，如果有一些重合，我想用 array2 的数据替换 array1 中的数据，例如从 array1 替换 {"Dates":"05/25/2021","valor ":"0"} array2 {Dates: "05/25/2021", count: "20"} 匹配的数据

array1 = [{Dates:"05/10/2021",count:"0"},{Dates:"05/11/2021",count:"0"},{Dates:"05/12/2021",count:"0"},{Dates:"05/13/2021",count:"0"},{Dates:"05/14/2021",count:"0"},{Dates:"05/15/2021",count:"0"},{Dates:"05/16/2021",count:"0"},{Dates:"05/17/2021",count:"0"},{Dates:"05/18/2021",count:"0"},{Dates:"05/19/2021",count:"0"},{Dates:"05/20/2021",count:"0"},{Dates:"05/21/2021",count:"0"},{Dates:"05/22/2021",count:"0"},{Dates:"05/23/2021",count:"0"},{Dates:"05/24/2021",count:"0"},{Dates:"05/25/2021",count:"0"},{Dates:"05/26/2021",count:"0"},{Dates:"05/27/2021",count:"0"},{Dates:"05/28/2021",count:"0"},{Dates:"05/29/2021",count:"0"},{Dates:"05/30/2021",count:"0"},{Dates:"05/31/2021",count:"0"},{Dates:"06/01/2021",count:"0"},{Dates:"06/02/2021",count:"0"},{Dates:"06/03/2021",count:"0"},{Dates:"06/04/2021",count:"0"},{Dates:"06/05/2021",count:"0"},{Dates:"06/06/2021",count:"0"},{Dates:"06/07/2021",count:"0"},{Dates:"06/08/2021",count:"0"}];

array2 = [{Dates: "05/25/2021", count: "20"},{Dates: "05/26/2021", count: "0"},{Dates: "05/27/2021", count: "3"},{Dates: "05/28/2021", count: "10"},{Dates: "06/07/2021", count: "0"}];

如果有人可以帮助我，我将不胜感激，谢谢

【问题讨论】：

标签： javascript typescript

【解决方案1】：

使用Array.find 和Array.forEach 的组合，您可以遍历array2 并更新array1 中的匹配对象。

array2.forEach(elm => {
  let match = array1.find(x => {
    return x.Dates == elm.Dates
  });
  if(typeof(match) != "undefined")
    match.count = elm.count;
});

完整的sn-p：

array1 = [{"Dates":"05/10/2021",count:"0"},{"Dates":"05/11/2021",count:"0"},{"Dates":"05/12/2021",count:"0"},{"Dates":"05/13/2021",count:"0"},{"Dates":"05/14/2021",count:"0"},{"Dates":"05/15/2021",count:"0"},{"Dates":"05/16/2021",count:"0"},{"Dates":"05/17/2021",count:"0"},{"Dates":"05/18/2021",count:"0"},{"Dates":"05/19/2021",count:"0"},{"Dates":"05/20/2021",count:"0"},{"Dates":"05/21/2021",count:"0"},{"Dates":"05/22/2021",count:"0"},{"Dates":"05/23/2021",count:"0"},{"Dates":"05/24/2021",count:"0"},{"Dates":"05/25/2021",count:"0"},{"Dates":"05/26/2021",count:"0"},{"Dates":"05/27/2021",count:"0"},{"Dates":"05/28/2021",count:"0"},{"Dates":"05/29/2021",count:"0"},{"Dates":"05/30/2021",count:"0"},{"Dates":"05/31/2021",count:"0"},{"Dates":"06/01/2021",count:"0"},{"Dates":"06/02/2021",count:"0"},{"Dates":"06/03/2021",count:"0"},{"Dates":"06/04/2021",count:"0"},{"Dates":"06/05/2021",count:"0"},{"Dates":"06/06/2021",count:"0"},{"Dates":"06/07/2021",count:"0"},{"Dates":"06/08/2021",count:"0"}];

array2 = [{Dates: "05/25/2021", count: "20"},{Dates: "05/26/2021", count: "0"},{Dates: "05/27/2021", count: "3"},{Dates: "05/28/2021", count: "10"},{Dates: "06/07/2021", count: "0"}];

array2.forEach(elm => {
  let match = array1.find(x => {
    return x.Dates == elm.Dates
  });
  if(typeof(match) != "undefined")
    match.count = elm.count;
});

console.log(array1);

【讨论】：

forEach 扩展方法比array2 上的map 更合适。我建议在设置 count 属性之前验证 array1.find 返回值。目前尚不清楚array2 日期是否保证在array1 中。
很公平。我已经更新了答案。
非常感谢你们

【解决方案2】：

作为一种天真的方法，我会这样做，这就是你要找的吗？

for(let i = 0; i < array1.length; i++) {
   for(let j = 0; j < array2.length; j++) {
      if(array1[i].Dates == array2[j].Dates)
         array1[i] = array2[j];
   }
}

【讨论】：

是的，两个答案都对我有很大帮助，非常感谢

【解决方案3】：

一种只对每个数组进行一次迭代的方法是使用 Dates 作为键从 array2 创建一个 Map，然后使用 Object.assign() 映射第一个数组。

如果 assign 方法中的 get() 未定义（未存储此类日期），它将忽略未定义并返回 array1 对象的原始值。

这避免了使用 find() 或嵌套 for 循环等方法的所有额外数组循环

const a2Map = new Map(array2.map(e => [e.Dates, e]))

const res = array1.map(e => Object.assign({}, e, a2Map.get(e.Dates)));

console.log(res);

<script>
array1 = [{"Dates":"05/10/2021",count:"0"},{"Dates":"05/11/2021",count:"0"},{"Dates":"05/12/2021",count:"0"},{"Dates":"05/13/2021",count:"0"},{"Dates":"05/14/2021",count:"0"},{"Dates":"05/15/2021",count:"0"},{"Dates":"05/16/2021",count:"0"},{"Dates":"05/17/2021",count:"0"},{"Dates":"05/18/2021",count:"0"},{"Dates":"05/19/2021",count:"0"},{"Dates":"05/20/2021",count:"0"},{"Dates":"05/21/2021",count:"0"},{"Dates":"05/22/2021",count:"0"},{"Dates":"05/23/2021",count:"0"},{"Dates":"05/24/2021",count:"0"},{"Dates":"05/25/2021",count:"0"},{"Dates":"05/26/2021",count:"0"},{"Dates":"05/27/2021",count:"0"},{"Dates":"05/28/2021",count:"0"},{"Dates":"05/29/2021",count:"0"},{"Dates":"05/30/2021",count:"0"},{"Dates":"05/31/2021",count:"0"},{"Dates":"06/01/2021",count:"0"},{"Dates":"06/02/2021",count:"0"},{"Dates":"06/03/2021",count:"0"},{"Dates":"06/04/2021",count:"0"},{"Dates":"06/05/2021",count:"0"},{"Dates":"06/06/2021",count:"0"},{"Dates":"06/07/2021",count:"0"},{"Dates":"06/08/2021",count:"0"}];

array2 = [{Dates: "05/25/2021", count: "20"},{Dates: "05/26/2021", count: "0"},{Dates: "05/27/2021", count: "3"},{Dates: "05/28/2021", count: "10"},{Dates: "06/07/2021", count: "0"}];

</script>

【讨论】：