I have an object myObject like this

 0:
    timestamp: 1525879470
    name: "testing"
    lastname: "testingdone"
 1: 
    timestamp: 1525879470
    name: "testing2"
    lastname: "testingdone2"

I am looking for a way to convert it to csv nicely like this

timestamp,name,lastname
1525879470,testing,testingdone
1525879470,testing2,testingdone2

Good news is I can extract the header

var headers = Object.keys(myObject.reduce(function (result, obj) {
                            return Object.assign(result, obj);
                        }, {}));

The headers var will give me an array of headers like

Array(3): timestamp, name, lastname

I am just looking to extract the values from the object maybe in an array like header, and then finally convert it into CSV as above. I tried using array map but for some reason I am not able to figure it out

I have an object myObject like this

 0:
    timestamp: 1525879470
    name: "testing"
    lastname: "testingdone"
 1: 
    timestamp: 1525879470
    name: "testing2"
    lastname: "testingdone2"

I am looking for a way to convert it to csv nicely like this

timestamp,name,lastname
1525879470,testing,testingdone
1525879470,testing2,testingdone2

Good news is I can extract the header

var headers = Object.keys(myObject.reduce(function (result, obj) {
                            return Object.assign(result, obj);
                        }, {}));

The headers var will give me an array of headers like

Array(3): timestamp, name, lastname

I am just looking to extract the values from the object maybe in an array like header, and then finally convert it into CSV as above. I tried using array map but for some reason I am not able to figure it out

• javascript
• csv

4 Answers 4

If that is array of objects you can first get header and then values and create string from that.

const data = [ {timestamp: 1525879470,name: "testing",lastname: "testingdone"
}, {timestamp: 1525879470,name: "testing2",lastname: "testingdone2"}]

let csv = '';
let header = Object.keys(data[0]).join(',');
let values = data.map(o => Object.values(o).join(',')).join('\n');

csv += header + '\n' + values;
console.log(csv)

A more simplified approach based on the examples above

// Sample data - two columns, three rows:
const data = [
  {code: 'HK', name: 'Hong Kong'},
  {code: 'KLN', name: 'Kowloon'},
  {code: 'NT', name: 'New Territories'},
];

// Transform an array of objects into a CSV string
const csv = function(data) {
  // Setup header from object keys
  const header = Object.keys(data[0]).join(",");

  // Setup values from object values
  const values = data.map(item => Object.values(item).join(","));

  // Concat header and values with a linebreak
  const csv = [header, ...values].join("\n");

  return csv;
};

// Setup file
const file = csv(data)

console.log({ file })

If that thing (myObject) is a JavaScript object, you can serialize it in array chunks using destructuring and then join them in a string using Array#reduce:

const data = {
  '0': {
    timestamp: 1525879470,
    name: "testing",
    lastname: "testingdone"
  },
  '1': {
    timestamp: 1525879470,
    name: "testing2",
    lastname: "testingdone2"
  }
};

const result = [
    // headers
    Object.keys(data['0']),
    // values
    ...Object.values(data).map(item => Object.values(item))
  ]
  .reduce((string, item) => {
    string += item.join(',') + '\n';
    return string;
  }, '');

console.log(result);

Be careful about writing your own code for CSV, there are a lot of edge cases and much more than just combine items with a comma and a newline (what if your data contains commas? how to insert the BOM to make sure your text with a non-ASCII input displays correctly in any spreadsheet software?).

Here's some working example code:

const ObjectsToCsv = require('objects-to-csv');

// Sample data - two columns, three rows:
const data = [
  {code: 'HK', name: 'Hong Kong'},
  {code: 'KLN', name: 'Kowloon'},
  {code: 'NT', name: 'New Territories'},
];

// If you use "await", code must be inside an asynchronous function:
(async () => {
  const csv = new ObjectsToCsv(data);

  // Save to file:
  await csv.toDisk('./test.csv');

  // Return the CSV file as string:
  console.log(await csv.toString());
})();