[SOLVED] React – How to convert a nested object into a array


This Content is from Stack Overflow. Question asked by Oliver

I have the following object that I would like to convert it into an array of object and each object from the array to have the key: value[0].


const obj = {
   comedy: ['book1', 'book2'],
   action: ['book3', 'book4'],
   drama: ['book5'],


const arr = [
{comedy: 'book1'},
{comedy: 'book2'},
{action: 'book3'},
{action: 'book4'},
{drama: 'book5'},

So far I have tried solving this with loops and using Object.entries. But I do not get the output I need.

let result = [];

for(const [key1, value1] of Object.entries(arr)) {
  for (const [key2, value2] of Object.entries(value1)) {
    if(result[key2]) {
      result[key2] [key1] = value2
    } else {
      result[key2] = {[key1]: value2}


I have also tried to loop recalling the function inside itself. (I have found this search for the answer). But it will get stucked in a infinite loop.

const result = [];

const getArray = (obj) => {
  if (!obj) return;

  const {keys, ...rest} = obj;

console.log('here', getArray(arr));


You could use a reduce over the entries of obj, adding objects to the accumulator for each entry in the array value:

const obj = {
  comedy: ['book1', 'book2'],
  action: ['book3', 'book4'],
  drama: ['book5'],

const arr = Object.entries(obj)
  .reduce((acc, [k, v]) => acc.concat(v.map(b => ({ [k] : b }))),

This Question was asked in StackOverflow by Oliver and Answered by Nick It is licensed under the terms of CC BY-SA 2.5. - CC BY-SA 3.0. - CC BY-SA 4.0.

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