javascript cannot map array of objects with nested values

Question

Trying to map array of objects with values nested in child objects structure like:

const objs = [{
        "B": {
            "value": 1,
        },
        "D": {
            "value": "45"
        },
        "E": {
            "value": "234"
        },
        "A": {
            "value": "543"
        },
        "C": {
            "value": "250"
        }
    },...]

to the structure like:

[
  { name: 'B', value: 1 }, 
  { name: 'D', value: '45' }, 
  { name: 'E', value: '234' }, 
  { name: 'A', value: '543' },
  { name: 'C', value: '250' }
]

and the result of the mapping is undefined

const mapped = objs.map((key, index) => {
  Object.keys(key).map(el => ({
    name: el
  }))
})

Example: Stackblitz

Answer 1

You should operate on objs[0], not objs, because it is an array of one object, not array of objects.

let array = []
for(let object in objs[0]){
array.push({
"name": object,
"value": objs[0][object].value
})
}

Answer 2

return is missing in Object.keys . As well instead of Object.keys use Object.entries to get key and value .

 const objs = [{ "B": { "value": 1, }, "D": { "value": "45" }, "E": { "value": "234" }, "A": { "value": "543" }, "C": { "value": "250" } }]; const mapped = objs.map((key, _) => { return Object.entries((key)).map(([name, { value }]) => ({ name, value })) }).flat(); console.log(mapped); 

Answer 3

You are missing return statement and value property definition.

Besides you may want to use flatMap instead of map in order to avoid a nested array in the result:

 const objs = [{ "B": { "value": 1, }, "D": { "value": "45" }, "E": { "value": "234" }, "A": { "value": "543" }, "C": { "value": "250" } }] const mapped = objs.flatMap((key, index) => { return Object.keys(key).map(el => ({ name: el, value: key[el].value })) }) console.log(mapped)