Concat json to promise: How to get additional key value pair in json object from promise pending

I manually concat a json object to a promise. The code below on the first print, cosole.log(new_response) gets me this, which is what I want

Promise { <pending>, a: '123' }

However the second print, cosole.log(data_json_array) gets me the json object without the key-value, a: '123'

I don't know why is that. I would like the json object to include the key-value a: '123' For example:

{ 
  key1: "1",
  key2: "2",
  a: "123
}

Thanks in advance.

Promise.all(somefunction(parameter)).then(function (responses) {

        return Promise.all(responses.map(function (response) {

            new_json = {a: "123"}
            var new_response = Object.assign(response.json(), new_json)
            console.log(new_response)
            return new_response

      }.then(function (data) {

        console.log(data)

    })

A slightly different approach could involve updating someFunction to handle the json() and handle merging the data with the provided url. This can help avoid nested Promise.all:

function someFunction(parameter) {
  // create array of promises
  return parameter.urls.map((url) =>
    fetch(url)
      // parse JSON
      .then((res) => res.json())
      // Merge data with url property
      .then((data) => ({ ...data, url }))
  );
}

Promise.all(
  someFunction({
    urls: [
      "https://jsonplaceholder.typicode.com/todos/1",
      "https://jsonplaceholder.typicode.com/todos/2",
    ],
  })
).then((data) => console.log(data));

Hopefully that helps!