javascript - 在 Object.keys(obj) 中只工作部分时间

Question

我试图查看某个数字是否在 Object.keys() 中，出于某种原因我得到了部分响应，其中一些数字未包含在最终对象中。知道为什么 in 在这里只部分起作用吗？

var arrayOfNumbersIHave = [
  "542009988",
  "7411111111",
  "542261111",
  "542009988",
  "7411111111",
  "7411111111",
  "7442334675",
  "661766029",
  "692549335",
]

var snapObject = {
  "542009988": "A",
  "542261111": "B",
  "661766029": "C",
  "6617666029": "D",
  "692549335": "E",
  "7442334675": "F",
  "7411111111": "G",
}

var objToDisplay = {};

for (const i in arrayOfNumbersIHave) {
  if (i in Object.keys(snapObject)) {
    objToDisplay[arrayOfNumbersIHave[i]] = snapObject[arrayOfNumbersIHave[i]]

  }
}

console.log(objToDisplay)

结果:

{
  "542009988": "A",
  "542261111": "B",
  "7442334675": "F",
  "7411111111": "G",
}

预期结果:

{
  "542009988": "A",
  "542261111": "B",
  "661766029": "C",
  "692549335": "E",
  "7442334675": "F",
  "7411111111": "G",
}

Answer 1

您可以避免使用 for..in 来迭代数组。或者，您可以在 arrayOfNumbersIHave 上使用 reduce & 在每次迭代中，curr 参数将代表 arrayOfNumbersIHave 的每个元素。使用此 curr 检查 snapObject 中是否存在同名的键。是这样然后在累加器对象中添加键和值

let arrayOfNumbersIHave = [
  "542009988",
  "7411111111",
  "542261111",
  "542009988",
  "7411111111",
  "7411111111",
  "7442334675",
  "661766029",
  "692549335",
]

let snapObject = {
  "542009988": "A",
  "542261111": "B",
  "661766029": "C",
  "6617666029": "D",
  "692549335": "E",
  "7442334675": "F",
  "7411111111": "G",
}

let objToDisplay = arrayOfNumbersIHave.reduce(function(acc, curr) {
  if (snapObject[curr]) {
    acc[curr] = snapObject[curr]
  }
  return acc;
}, {}) // {} is accumulator object 

console.log(objToDisplay)