Adding new sets of key and value from array of object-CodePudding

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'}]

CodePudding user response：

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

CodePudding user response：

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)

CodePudding user response：

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);