Converting an array of arrays to list of JSON objects instead of JSON strings

Question

I'm trying to convert an array of arrays to a list of JSON objects.

var headers = ['first name','last name','age']

var data = [ [ 'John', 'Gill', '21' ], [ 'Sai', 'Varun', '21' ] ]

When we use the above two lists to generate a list of JSON's, output will be like,

[ { 'First name': 'John', 'Last name': 'Gill', age: '21' },
  { 'First name': 'Sai', 'Last name': 'Varun', age: '21' } ]

But I'm in need of the output to be as, (double quoted strings and the JSON should not be a string but should be a JSON object)

[ {"First name":"John","Last name":"Gill","age":"21"},
  {"First name":"Sai","Last name":"Varun","age":"21"} ]

I tried using JSON.stringify but the result won't be a JSON object right, it'll be a JSON string which would prevent accessing each of the JSON's from the list as a whole.

I have gone through many such answers but in vain. Can someone shed some light on this?!

I have tried using JSON.stringify which I have already mentioned in the answer. — Wasim Thabraze
– Wasim Thabraze, Commented Feb 23, 2017 at 10:32

Nina Scholz · Accepted Answer · 2017-02-23 10:41:39Z

You could generate an array with the objects first and the stringify the array.

var headers = ['first name', 'last name', 'age'],
    data = [['John', 'Gill', '21'], ['Sai', 'Varun', '21']],
    result = data.map(function (a) {
        var object = {};
        headers.forEach(function (k, i) {
            object[k] = a[i];
        });
        return object;
    });
    
console.log(JSON.stringify(result));
console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

ES6

var headers = ['first name', 'last name', 'age'],
    data = [['John', 'Gill', '21'], ['Sai', 'Varun', '21']],
    result = data.map(a => headers.reduce((r, k, i) => Object.assign(r, { [k]: a[i] }), {}));
    
console.log(JSON.stringify(result));
console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Mirko Vukušić · Accepted Answer · 2017-02-23 10:37:34Z

2

var headers = ['first name','last name','age']
var data = [ [ 'John', 'Gill', '21' ], [ 'Sai', 'Varun', '21' ] ]

function createItem(item) {
    newObject = {}
    item.map((val,i)=>newObject[headers[i]]=val)
	return newObject
}

console.log(data.map(item=>createItem(item)))

answered Feb 23, 2017 at 10:37

Mirko Vukušić

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1 Comment

Mirko Vukušić Over a year ago

Wanted to say Nina's solution is much more elegant, shorter and faster. But was surprised it's a bit (35%) slower after all: jsbench.me/u9iziasjz2/1

Rohìt Jíndal · Accepted Answer · 2017-02-23 18:28:00Z

0

DEMO

var headers = ['first name','last name','age'];

var data = [['John', 'Gill', '21'],['Sai', 'Varun', '21']];

var res = data.map(function(item) {
  var obj = {};
  for (var i in headers) {
    obj[headers[i]] = item[i];
  }
  return obj;
});

console.log(res);

answered Feb 23, 2017 at 18:28

Rohìt Jíndal

27.4k16 gold badges80 silver badges133 bronze badges

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