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Javascript – How to traverse an array and add a field into json

Wonder if someone can help me traverse this array so that the cardNumber can be included in the deviceListJson.

So at the moment I have two json files which I read off.

const deviceListData = await readJSON(deviceFilePath);
const playerListData = await readJSON(playersFilePath);

deviceFilePath contains all the devices like so:

{
    "deviceId": "9331d5fwwd77",
    "slot": 1,
    "deviceType": "GAME"
},
{
    "deviceId": "9221d5fwwd77",
    "slot": 3,
    "deviceType": "GAME"
},
{
    "deviceId": "9001d5fwwd77",
    "slot": 10,
    "deviceType": "GAME"
},
{
    "deviceId": "9331d5fww007",
    "slot": 11,
    "deviceType": "GAME"
},
{
    "deviceId": "9331d5f00077",
    "slot": 19,
    "deviceType": "GAME"
}

PlayerListData contains all the player info json like so:

{
    "cardNumber": "199",
    "firstName": "TIM",
    "middleName": "P",
},
{
    "cardNumber": "110",
    "firstName": "JACK",
    "middleName": "Z",
},
{
    "cardNumber": "111",
    "firstName": "MICKEY",
    "middleName": "A",
}

What I want to do is simply add a random card number from the playerListData Json into the deviceListData Json.

So for example deviceListData json will look like this:

{
    "deviceId": "9331d5fwwd77",
    "slot": 1,
    "deviceType": "GAME",
    "cardNumber": "111"
},
{
    "deviceId": "9221d5fwwd77",
    "slot": 3,
    "deviceType": "GAME",
     "cardNumber": "110"
},
{
    "deviceId": "9001d5fwwd77",
    "slot": 10,
    "deviceType": "GAME",
     "cardNumber": "199"
},
{
    "deviceId": "9331d5fww007",
    "slot": 11,
    "deviceType": "GAME",
    "cardNumber": "199"
},
{
    "deviceId": "9331d5f00077",
    "slot": 19,
    "deviceType": "GAME",
    "cardNumber": "111"
}

So I do a map like so:

const cardNumber = playerListData.map((item) => item.cardNumber);
console.log(cardNumber);

And it outputs this array (I notice it doesn’t include the key, just the values in the array of the card numbers)

[ '199', '110', '111' ]

When I piece together the whole code, what happens is that it adds all of the fields from the playerListJson into DeviceListJson like so:

{
    "deviceId": "9331d5fwwd77",
    "slot": 1,
    "deviceType": "GAME",
    "cardNumber": "111",
    "firstName": "MICKEY",
    "middleName": "A"
},
{
    "deviceId": "9221d5fwwd77",
    "slot": 3,
    "deviceType": "GAME",
    "cardNumber": "110",
    "firstName": "JACK",
    "middleName": "Z"
},
{
    "deviceId": "9001d5fwwd77",
    "slot": 10,
    "deviceType": "GAME",
    "cardNumber": "199",
    "firstName": "TIM",
    "middleName": "P"
},
{
    "deviceId": "9331d5fww007",
    "slot": 11,
    "deviceType": "GAME",
    "cardNumber": "199",
    "firstName": "TIM",
    "middleName": "P"
},
{
    "deviceId": "9331d5f00077",
    "slot": 19,
    "deviceType": "GAME",
    "cardNumber": "111",
    "firstName": "MICKEY",
    "middleName": "A"
}

This is the code:

export async function assignPlayerCards() {
  try {
    const deviceListData = await readJSON(deviceFilePath);
    const playerListData = await readJSON(playersFilePath);
    const cardNumber = playerListData.map((item) => item.cardNumber);
    

    // Function to get a random card number from player list json
    function getRandomJson1Element() {
      const randomIndex = Math.floor(Math.random() * cardNumber.length);
      // console.log(cardNumber[randomIndex]);
      return playerListData[randomIndex];
    }

    // Update each element in device JSON with a random card number from player list JSON
    deviceListData.forEach((element) => {
      const randomElement = getRandomJson1Element();
      Object.assign(element, randomElement);
    });

   
    await writeJSON(deviceFilePath, deviceListData);
    console.log("Headers set for devices");
  } catch (error) {
    throw error;
  }
}

What am I doing wrong and how can I get it to meet my requirement which is to just add the cardNumber into the deviceListJson?

Tags:

2

Answers


  1. 0

    Right now you’re adding all fields with Object.assign, what you want to do is to only add one field, so you could replace your forEach loop:

    // Update each element in device JSON with a random card number from player list JSON
deviceListData.forEach((element) => {
  const randomElement = getRandomJson1Element();
  Object.assign(element, randomElement);
});

    with the following:

    // Update each element in device JSON with a random card number from player list JSON
deviceListData.forEach((element) => {
  element.cardNumber = getRandomJson1Element().cardNumber;
});
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  2. 0

    Select random index from array playerListData

    Math.floor(Math.random() * playerListData.length);

    And with mapping deviceListData array and over each one and with destructing build another object with cardNumber property selected from randomly player.

    const deviceListData=[{ "deviceId": "9331d5fwwd77", "slot": 1, "deviceType": "GAME" }, { "deviceId": "9221d5fwwd77", "slot": 3, "deviceType": "GAME" }, { "deviceId": "9001d5fwwd77", "slot": 10, "deviceType": "GAME" }, { "deviceId": "9331d5fww007", "slot": 11, "deviceType":
"GAME" }, { "deviceId": "9331d5f00077", "slot": 19, "deviceType": "GAME" }];
const playerListData = [{ "cardNumber": "199", "firstName": "TIM", "middleName": "P", }, { "cardNumber": "110", "firstName": "JACK", "middleName": "Z", }, { "cardNumber": "111", "firstName": "MICKEY", "middleName": "A", }];

const result = deviceListData.map(device => {
  const randomIndex = Math.floor(Math.random() * playerListData.length);
  const randomPlayer = playerListData[randomIndex];
  return { ...device,
    cardNumber: randomPlayer.cardNumber
  };
});
console.log(result)
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