How do I get into the array I got from json?-CodePudding

I have a JSON file. I'm pulling data from this file with fetch. But I want to get the first element in all the elements of the array I pulled. I tried this but couldn't find it. Can you help me ?

MY JSON DATA :

{
    "cols": [
        "Name Surname",
        "Company",
        "Email",
        "Date",
        "Country",
        "City"
    ],
    "data": [
        [
            "Hyacinth Vincent",
            "Duis Corporation",
            "[email protected]",
            "28/06/2022",
            "Eritrea",
            "Lyubertsy"
        ],
        [
            "Brenden Martinez",
            "Volutpat Nunc Associates",
            "[email protected]",
            "24/03/2021",
            "British Indian Ocean Territory",
            "Colwood"
        ],
        [
            "Lunea Kinney",
            "Ornare Facilisis Eget Incorporated",
            "[email protected]",
            "20/10/2021",
            "Jordan",
            "Yorkton"
        ],
        [
            "Rhona Mooney",
            "Sed Et PC",
            "[email protected]",
            "10/11/2020",
            "Azerbaijan",
            "Shrewsbury"
        ]
    ]
}

MY JS CODE :

fetch("api/tesodev.json")
  .then((response) => response.json())
  .then((data) => {
    let cols = data.cols;
    let responseData = data.data;
  for (let index = 0; index < responseData.length; index  ) {
    let newResponseData = responseData.map(function (el, i) {
        console.log(el[i]);
      });
      
  }
    console.log(cols[0]);
  });

Exactly what I'm trying to do is to get to the first elements of all the elements of the data array. I want to access the data of "Hyacinth Vincent", "Brenden Martinez", "Lunea Kinney", "Rhona Mooney".

CodePudding user response：

The only thing you're doing wrong is mapping over the whole child array and logging every part of it, when what you want is the first element:

const data = {
  "cols": [
    "Name Surname",
    "Company",
    "Email",
    "Date",
    "Country",
    "City"
  ],
  "data": [
    [
      "Hyacinth Vincent",
      "Duis Corporation",
      "[email protected]",
      "28/06/2022",
      "Eritrea",
      "Lyubertsy"
    ],
    [
      "Brenden Martinez",
      "Volutpat Nunc Associates",
      "[email protected]",
      "24/03/2021",
      "British Indian Ocean Territory",
      "Colwood"
    ],
    [
      "Lunea Kinney",
      "Ornare Facilisis Eget Incorporated",
      "[email protected]",
      "20/10/2021",
      "Jordan",
      "Yorkton"
    ],
    [
      "Rhona Mooney",
      "Sed Et PC",
      "[email protected]",
      "10/11/2020",
      "Azerbaijan",
      "Shrewsbury"
    ]
  ]
}

let cols = data.cols;
let responseData = data.data;
for (let index = 0; index < responseData.length; index  ) {
  console.log(responseData[index][0])
}

(I would strongly suggest you change your data format; an array of objects would be much less fragile:

    ...
    "data": [
        {
            name: "Hyacinth Vincent",
            company: "Duis Corporation",
            email: "[email protected]",
            date: "28/06/2022",
            country: "Eritrea",
            city: "Lyubertsy"
        },
        {
          ...

CodePudding user response：

You can use a double index to access the first field. [i][0] will access the first field in the ith object,

let responseData = <json>;

for (let index = 0; index < responseData.length; index  ) {
    console.log(responseData[i][0]);
}

CodePudding user response：

You need to access the current row in your for loop, then access the first element of this row.

fetch("api/tesodev.json")
  .then((response) => response.json())
  .then((data) => {
    let cols = data.cols;
    let responseData = data.data;
    for (let index = 0; index < responseData.length; index  ) {
      const myDataRow = responseData[index];
      const theFirstDataOfMyRow = myDataRow[0];
      console.log(theFirstDataOfMyRow); 
    }
    console.log(cols[0]);
  });

CodePudding user response：

You're almost doing it the way you want it work.

const data = {
    "cols": [
        "Name Surname",
        "Company",
        "Email",
        "Date",
        "Country",
        "City"
    ],
    "data": [
        [
            "Hyacinth Vincent",
            "Duis Corporation",
            "[email protected]",
            "28/06/2022",
            "Eritrea",
            "Lyubertsy"
        ],
        [
            "Brenden Martinez",
            "Volutpat Nunc Associates",
            "[email protected]",
            "24/03/2021",
            "British Indian Ocean Territory",
            "Colwood"
        ],
        [
            "Lunea Kinney",
            "Ornare Facilisis Eget Incorporated",
            "[email protected]",
            "20/10/2021",
            "Jordan",
            "Yorkton"
        ],
        [
            "Rhona Mooney",
            "Sed Et PC",
            "[email protected]",
            "10/11/2020",
            "Azerbaijan",
            "Shrewsbury"
        ]
    ]
}

// Simplyfied, get data, use only data, only putput first entry in the array.
data.data.forEach((person) => {
  console.log(person[0])
})

// Would be something like this:
/*
fetch("api/tesodev.json")
  .then((response) => response.json())
  .then((data) => {
    let cols = data.cols
    let persons = data.data
    for (i = 0; i < persons.length; i  ) {
      console.log(persons[i][0])
    }
  })
*/

CodePudding user response：

ummm...

I think there are multiple problems in this newResponseData will be array of item having values undefined as console.log() returns undefined.

I think this two lines can help. Can you check at your end

 let responseData = data.data;
  const finaldata = responseData.map(item => item [0])