javascript - 将数组保存为键中的值并循环遍历它们以获取键

Question

如果我输入任何变量，我希望能够使用 getValue 并迭代 myObject 键来获取键值“f”。

result = "f"; 

或者

result = " g";

const myObject = {
  "f": [1, 2, 3, 4, 5],
  "g": [6, 7, 8, 9, 10]
};
let getValueOne = 1;

function getKeyByValue() {
  for (let i = 0; i < myObject[value].length; i++) {
    result = myObject.key[i];
    if (i === getValueOne) {
      console.log(result);
    }
  }
}

Answer 1

您的意思是找到包含该值的数组的键？

const getByValue = (obj,val) => Object.entries(obj)
  .filter(([key,arr]) => arr.includes(val))
  .map(([key,arr]) => key)[0] ?? "N/A";
const myObject = {
  "f": [1, 2, 3, 4, 5],
  "g": [6, 7, 8, 9, 10]
};
console.log(getByValue(myObject,1))
console.log(getByValue(myObject,99))
console.log(getByValue(myObject,6))

备选

const getByValue = (obj,val) => Object.entries(obj)
  .reduce((acc,[key,arr]) => (arr.includes(val) && acc.push(key),acc),[])[0] ?? "N/A";
  
const myObject = {
  "f": [1, 2, 3, 4, 5],
  "g": [6, 7, 8, 9, 10]
};
console.log(getByValue(myObject,1))
console.log(getByValue(myObject,99))
console.log(getByValue(myObject,6))

使用查找表(灵感来自 vitaly-t's 答案)

这是假设所有数组的值都是唯一的

const makeLookup = obj => Object.entries(obj).reduce((acc,[key,arr]) => (arr.forEach(val => acc[val] = key),acc),{});
const getByValue = (tbl,val) => tbl[val] ?? "N/A";
const myObject = {
  "f": [1, 2, 3, 4, 5],
  "g": [6, 7, 8, 9, 10]
};

const lookUp = makeLookup(myObject);
console.log(JSON.stringify(lookUp))

console.log(getByValue(lookUp,1))
console.log(getByValue(lookUp,99))
console.log(getByValue(lookUp,6))