Javascript array value undefined?

Question

I am currently working on a REST API / website project, where my REST API has to return an array of objects from the server, via a response and using GSON to make a Json array out of the data. However, when trying to get values from the javascript array for the website, I keep getting undefined. This is the array:

var userArr =[
  {
    "0x1": {
      "firstName": "Test1",
      "lastName": "Test1",
      "hobbies": [
        {
          "id": 1,
          "name": "Fodbold",
          "people": [
            "0x1"
          ]
        }
      ],
      "id": 1,
      "address": {
        "id": 1,
        "street": "Street1",
        "cityInfo": {
          "id": 1,
          "zipCode": "0555",
          "city": "Scanning"
        },
        "infoList": [
          "0x1",
          "0x2"
        ]
      },
      "phones": [
        {
          "id": 1,
          "number": "123124",
          "info": "0x1"
        }
      ]
    }
];

When I try to call userArr[0].firstName, I get an error saying that it's undefined, even though the data is there. This is from a get call, which I am doing in my javascript from my REST API, which sends back this specific array. I have tried looping through the array, with multiple objects inside, however I am unable to retrieve any info at all.

You should do userArr[0]["0x1"].firstName, you have two nested objects — Telokis
– Telokis, Commented Mar 16, 2017 at 3:40

Yeldar Kurmangaliyev · Accepted Answer · 2017-03-16 03:39:34Z

Your userArr is an array of objects which do not have firstName property. They have only one property named 0x1 for some reason. And this 0x1 property has firstName property.

You can access firstName of 0x1 property using this notation:

userArr[0]["0x1"].firstName

Here is the working demo:

var userArr = [{
  "0x1": {
    "firstName": "Test1",
    "lastName": "Test1",
    "hobbies": [{
      "id": 1,
      "name": "Fodbold",
      "people": [
        "0x1"
      ]
    }],
    "id": 1,
    "address": {
      "id": 1,
      "street": "Street1",
      "cityInfo": {
        "id": 1,
        "zipCode": "0555",
        "city": "Scanning"
      },
      "infoList": [
        "0x1",
        "0x2"
      ]
    },
    "phones": [{
      "id": 1,
      "number": "123124",
      "info": "0x1"
    }]
  }
}];

console.log(userArr[0]["0x1"].firstName);

By the way, there is a missing closing } bracket in the end of the array in your code.

anis programmer · Accepted Answer · 2017-03-16 04:07:31Z

1

I think if you write this code this way it is easy to understand and find the problem

var userArr =[
  {
    "0x1": {
      "firstName": "Test1",
      "lastName": "Test1",
      "hobbies": [{"id": 1,"name": "Fodbold","people": ["0x1"]}],
      "id": 1,
      "address": {"id": 1,"street": "Street1","cityInfo": {"id": 1,"zipCode": "0555","city": "Scanning"},
      "infoList": ["0x1","0x2"]},
      "phones": [{"id": 1,"number": "123124","info": "0x1"}]
    }
  }
];

You also missing the last second bracket. Then you could use this console.log(userArr[0]["0x1"].firstName);

answered Mar 16, 2017 at 4:07

anis programmer

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Comments

Faraz Babakhel · Accepted Answer · 2017-03-16 03:43:05Z

0

try this one

userArr[0]["0x1"].firstName

answered Mar 16, 2017 at 3:43

Faraz Babakhel

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Comments

Ngoan Tran · Accepted Answer · 2017-03-16 03:48:22Z

Incase value "0x1" is dynamic, you can access it by using Object.keys(userArr[0])[0] to get the first key of the object.

Here is solution:

var userArr = [{
  "0x1": {
    "firstName": "Test1",
    "lastName": "Test1",
    "hobbies": [{
      "id": 1,
      "name": "Fodbold",
      "people": [
        "0x1"
      ]
    }],
    "id": 1,
    "address": {
      "id": 1,
      "street": "Street1",
      "cityInfo": {
        "id": 1,
        "zipCode": "0555",
        "city": "Scanning"
      },
      "infoList": [
        "0x1",
        "0x2"
      ]
    },
    "phones": [{
      "id": 1,
      "number": "123124",
      "info": "0x1"
    }]
  }
}];

console.log(userArr[0][Object.keys(userArr[0])[0]].firstName);

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