am stuck now for the whole day and cannot get any further. I know, that I am missing a small thing, but just can't find it.

I got two arrays:

arrKeys = ["a", "b", "c"]
arrValues = [ 1, 2, 3, 4, 5, 6, 7, 8, 9]

I would like to get an array of objects, that looks like:

myObj = [
 {
  "a": 1,
  "b": 2,
  "c": 3
 },
 {
  "a": 4,
  "b": 5,
  "c": 6
 },
 {
  "a": 7,
  "b": 8,
  "c": 9
 }
]

I tried to do something like:

const myObj = arrKeys.reduce((newObj, key, index) => {
  if (arrValues[index] == undefined) arrValues[index] = null
  newObj[key] = aarValues[index]
  return newObj
}, {})
cosnole.log(myObj)

But the problem is, that arrKeys is looping only once and I do not know, how to "reset" the counter each time arrKeys gets to max length. Also I got only an object back, not an array of objects:

My result

myObj = {
  "a": 1,
  "b": 2,
  "c": 3
 }

Any ideas are really appreaciated.

CodePudding user response：

You can use modulo operator to get check for every keys.length nth element and then add a new object by slicing the values array where the start is current index and end current index keys.length

const f = (keys, values) => values.reduce((r, e, i) => {
  if (i % keys.length === 0) {
    const index = i / keys.length
    r[index] = values.slice(i, i   keys.length).reduce((r, e, i) => {
      r[keys[i]] = e
      return r
    }, {})
  }

  return r
}, [])

console.log(f(["a", "b", "c"], [1, 2, 3, 4, 5, 6, 7, 8, 9]))
console.log(f(["a", "b", "c", 'g'], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]))
console.log(f(["a", "b"], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]))

CodePudding user response：

You can iterate over the values, creating arrKeys.length chunks at a time, and then creating an object from the chunk by mapping the chunk index to the appropriate key. This approach has the advantage that if arrValues is not an exact multiple of arrKeys length, it will still work:

const f = (arrKeys, arrValues) => {
  const result = []
  const kLen = arrKeys.length
  const vLen = arrValues.length
  for (i = 0; i < vLen; i  = kLen) {
    chunk = arrValues.slice(i, i   kLen)
    result.push(Object.fromEntries(chunk.map((v, i) => [arrKeys[i], v])))
  }
  return result;
}

console.log(f(["a", "b", "c"], [1, 2, 3, 4, 5, 6, 7, 8, 9]))
console.log(f(["a", "b", "c"], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]))
console.log(f(["a", "b", "c", "d"], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]))

CodePudding user response：

One way would be to loop through the arrValues using a conventional for...loop.

We can use the modulus operator % to determine where we are in the run of three.

Check the below for a demo:

var arrKeys = ["a", "b", "c"];
var arrValues = [ 1, 2, 3, 4, 5, 6, 7, 8, 9];

var myObj = [];
var newObj = null;
for(var i=0; i<arrValues.length; i  )
{
  if(i % 3 === 0) // First run of three
    newObj = {};

  newObj[ arrKeys[i % 3] ] = arrValues[i];
  
  if(i % 3 === 2) // We're at the end of the run of three
    myObj.push(newObj);
}
console.log(myObj);

CodePudding user response：

i do this with reduce

const arrKeys = ["a", "b", "c"]
const arrValues = [ 1, 2, 3, 4, 5, 6, 7, 8, 9]
let myObj = [];

arrValues.reduce((pre, cur,i) => {
    pre[arrKeys[i % 3]] = cur;
    if (i % 3 === 2) {
        myObj.push(pre);
        return {};
    } else return pre;
}, {})

console.log(myObj)

CodePudding user response：

you can do that...

const
  arrKeys   = ['a', 'b', 'c']
, arrValues = [ 1, 2, 3, 4, 5, 6, 7, 8, 9]
, myObj = arrValues.reduce((r,v,i) => 
  {
  if (!(i%3)) r.a.push(r.o = {})  
  r.o[arrKeys[i%3]] = v
  return r
  },{ o:null,a:[] }).a
  ; 
console.log(myObj)