Convert array to object with similar key/value pairs

Question

I have an array of values as follows

[
    {
      "factor": {
        "data": "f1",
        "val": [
          "val1"
        ]
      }
    },
    {
      "factor": {
        "data": "f2",
        "val": [
          "val2"
        ]
      }
    }
  ]

Is there a way to convert it to below format

{
    "keyvalue": {
        "factor": {
            "data": "f1",
            "val": ["val1"]
        },
        "factor": {
            "data": "f2",
            "val": ["val2"]
        }
    }
}

Standard array parsing to object doesn't work in this case given keys has to be unique

Answer 1

It's impossible. Every key in the object has to be unique. To understand this, imagine you have an object with two identical keys:

const obj = {
  "key": 1,
  "key": 2
}

But what you should receive when you use an expression like obj.key ? 1 or 2 ? It's nonsense.

You should rethink your object structure, maybe you need an array of objects?

{
  "keyvalue": {
    "factor": [
      {
        "data": "f1",
        "val": ["val1"]
      },
      {
        "data": "f2",
        "val": ["val2"]
      }
    ]
  }
}

Answer 2

What you can do is use the data field as a key given it's always unique.

Something like this :

{
    "factor": {
        "f1": ["val1"],
        "f2": ["val2"]
    }
}

Here's how you would proceed to transform the array to the key/value object :

let keyValue = {"factor": {}};
theArray.forEach((item) => {
    const key = item.factor.data;
    const value = item.factor.val;
    keyValue.factor[key] = value;
});

now the keyValue object is as described.