从 object 的数组中添加新的键和值集

Question

im not yet expert in javascript but I wanted to add a new property in an array of objects with different values which is in an array format.

const mainArray = [{name: 'John', age: 30}, {name: 'Jane', age: 25}]

const country = ['Germany', 'Japan']

const res = mainArray.map(x => {
    return {
        name: x.name,
        age: x.age,
        country: country
    }
})

i tried this but its not working

expected to be like this

result = [{name: 'John', age: 30, country: 'Germany'}, {name: 'Jane', age: 25, country: 'Japan'}]

Answer 1

from your sample code, you actually setting the value of country with the whole array. you should use index

const mainArray = [{name: 'John', age: 30}, {name: 'Jane', age: 25}];
const country = ['Germany', 'Japan']

function addKey(arr, key, value) => {
  const res = arr.map((x, index) => {
    return {
      ...x,
      [key]: value[index]
    };
  });
  return res;
};

console.log(addKey(mainArray, 'country', country))

from here, you can add any other specific property in the second arg

hope this help you

Answer 2

You need to use index variable to access the values from other array

 const mainArray = [{name: 'John', age: 30}, {name: 'Jane', age: 25}]; const country = ['Germany', 'Japan'] const res = mainArray.map((x,i) => { return { name: x.name, age: x.age, country: country[i] // <-- i added [i] } }) console.log(res)

Answer 3

If the index of the country element is meant to be related to the index of mainArray , you can use the overload of .map with the index parameter,

modified: to account for country array not containing enough elements to match with your mainArray :

 const mainArray = [{name: 'John', age: 30}, {name: 'Jane', age: 25}] const country = ['Germany', 'Japan'] //use the overload of.map with the index, so you can set the new //property to the value of the country array via the index parameter const res = mainArray.map((x, index) => { return { name: x.name, age: x.age, country: country[index] || 'unknown' } }); console.log(res);