如何基于JavaScript中的条件将属性添加到对象的属性？

Question

我有2个数组，如下所示：

arr = [
  { "zc": 33004, "score": 32.61 },
  { "zc": 33005, "score": 88.51 },
  ...
]

arr2 = [
  "type": "feature", properties: { "zc": 33004 }, geometry: { ... },
  "type": "feature", properties: { "zc": 33005}, geometry: { ... }, 
  "type": "feature", properties: { "zc": 33009}, geometry: { ... }
]

expected result = [
  "type": "feature", properties: { "zc": 33004, "score": 32.61 }, geometry: { ... },
  "type": "feature", properties: { "zc": 33005, "score": 88.51 }, geometry: { ... }, 
  "type": "feature", properties: { "zc": 33009, "score": 0 }, geometry: { ... }
]

在这里，如果第二个数组zc在每个对象数组的properties对象内匹配，我想从第一个数组添加score 。

我正在使用扩展运算符编写一段代码，如下所示

  arr.forEach(ele => {
      arr2.forEach(element => {
        element = {
          ...element,
          ...((ele.zipcode==element.properties.zipcode) ? {element.properties.scope: ele.zipcode} : {element.properties.scope: 0})
        }
      });
    }) 
  console.log(arr2);

但出现编译时错误。 我在哪里做错了？

Answer 1

您可以使用reduce来为arr创建一个临时对象。 使用zc作为键，将score作为值。 这将使检查zc存在变得更加容易。

使用map循环通过arr2

 let arr = [{"zc":33004,"score":32.61},{"zc":33005,"score":88.51}] let arr2 = [{"type":"feature","properties":{"zc":33004},"geometry":{}},{"type":"feature","properties":{"zc":33005},"geometry":{}},{"type":"feature","properties":{"zc":33009},"geometry":{}}] let tempArr = arr.reduce((c, v) => Object.assign(c, {[v.zc]: v.score}), {}) let result = arr2.map(o => { o = {...o} //shallow copy the object o.properties = {...o.properties,score: tempArr[o.properties.zc] || 0} return o; }) console.log(result); 

Answer 2

由于无法在对象属性名称（例如{ element.properties.scope: ... } ）内使用点，因此会出现编译错误。因此，应按以下步骤进行操作：

arr.forEach(arrElem =>
  arr2.forEach(arr2Elem =>
    arr2Elem.properties = {
      ...arr2Elem.properties,
      ...{
        score: arrElem.zipcode === arr2Elem.properties.zipcode ? arrElem.score : 0
      }
    }
  );
);

console.log(arr2);

但是，我认为这不是正确的方法。 我认为您应该使用find() ，如下所示：

arr2.forEach(arr2Elem =>
  arr2Elem.properties = {
    ...arr2Elem.properties,
    ...{
      score: (arr.find(arrElem => arrElem.zipcode === arr2Elem.properties.zipcode) || { score: 0 }).score
    }
  }
);

console.log(arr2);

（我没有直接更改arr2Elem ，但是我更改了它的属性properties因为散布运算符不能与子对象一起使用）。