how to convert an array of objects into an array

Question

I have the following array of object.

response: [0] 
          Data: '455'
          [1]
          Data: '456'
          [2]
          Data: '457'


var normalizedArray = newlist.map(function (obj) {
                    return obj.Data;
                });

I am able to convert the above array of Object into an array 'notmalizedArray' using the above function. this works and gives me following output.

normalizedArray= ['455', '456', '457'];

If instead of only 1 element, i have following array of objects.

response: [0] 
          Data: '455'
          Note: 'tre'
          Id: '4'
          [1]
          Data: '456'
          Note: 'bre'
          Id: '5'
          [2]
          Data: '457'
          Note: 'cre'
          Id: '6'

I want the following array output for the above array of objects.

normalizedArray = ['455', 'tre', '4', '456', 'bre', '5', '457', 'cre', '6']

Can someone let me know what should be changed in the below function to achive above shown normalizedArray.

var normalizedArray = newlist.map(function (obj) {
                return obj.Data;
            });

Can you show what you have tried first?

evolutionxbox
– evolutionxbox

2017-01-24 00:13:23 +00:00
Commented Jan 24, 2017 at 0:13 — evolutionxbox
– evolutionxbox, Commented Jan 24, 2017 at 0:13

lonesomeday · Accepted Answer · 2017-01-24 00:23:03Z

1

The simplest way to do this is to build up an array of arrays and then flatten them.

First, let's build the array, using map just as you did:

// ES6
let normalizedArr = response.map(function({Data, Note, Id}) {
    return [Data, Note, Id];
});
// before ES6
var normalizedArr = response.map(function(obj) {
    return [obj.Data, obj.Note, obj.Id];
});

Then we flatten it. There is no flatten Javascript function: we simply append each array in turn onto an empty array using Array#concat:

// ES6
let finalArr = [].concat(...normalizedArr);
// before ES6
var finalArr = Array.prototype.concat.apply([], normalizedArr);

answered Jan 24, 2017 at 0:23

lonesomeday

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Comments

K D · Accepted Answer · 2017-01-24 00:27:50Z

1

try following

var normalizedArray = newlist.map(function (obj) {
                return [obj.Data,obj.Note,obj.Id];
            });

var res = [];
normalizedArray .forEach(function(arr){res = res.concat(arr);})
console.log(res)

answered Jan 24, 2017 at 0:27

K D

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Comments

Gruff Bunny · Accepted Answer · 2017-01-24 14:08:24Z

1

Here's a solution using underscore's map and values functions. The result of the map will be an array of arrays so flatten is then used to get one array:

var result = _.chain(response)
    .map(_.values)
    .flatten()
    .value();

edited Jan 24, 2017 at 14:08

answered Jan 24, 2017 at 9:15

Gruff Bunny

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Comments

Trash Can · Accepted Answer · 2017-01-24 00:23:51Z

0

var normalizedArray = newlist.reduce(function (resultArray, nextObj) {
                          resultArray.push(nextObj.Data, nextObj.Note, nextObj.Id);
                          return resultArray;
                      }, []);

Array.prototype.reduce() takes a reduction function and an initial value which is passed as the first parameter to that reduction function, the second argument is the next element in the array. Because we want to produce an array in the end, that's why there is a [] there

answered Jan 24, 2017 at 0:23

Trash Can

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Comments

Yaser · Accepted Answer · 2017-01-24 00:26:39Z

0

You can use the concat to do it:

var myArray = [
  {
   Data:  '455',
    Note: 'tre',
    Id: '4'
  }, {
    Data: '456',
    Note: 'bre',
    Id: '5'
  }, {
    Data: '457',
    Note: 'cre',
    Id: '6'
  }
];



var arr = myArray.map(function(obj)
 {
     return Object.keys(obj).map(function (key) { return obj[key]; });;
  });

var merged = [].concat.apply([], arr);

console.log(merged);

answered Jan 24, 2017 at 0:26

Yaser

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Fan Jin · Accepted Answer · 2017-01-24 00:33:08Z

0

With those code below, no matter the array objects have how many keys, the result will always be a flattened array.

// ES5
var normalizedArray = [];
response.forEach(function(obj) {
   Object.keys(obj).forEach(function(ele) {
      normalizedArray.push(obj[ele]);
   });
});
console.log(normalizedArray); // => ['455', 'tre', '4', '456', 'bre', '5', '457', 'cre', '6']

// ES6 one liner
let normalizedArray = [];
response.forEach(obj => Object.keys(obj).forEach(ele => normalizedArray.push(obj[ele])));

console.log(normalizedArray); // => ['455', 'tre', '4', '456', 'bre', '5', '457', 'cre', '6']

edited Jan 24, 2017 at 0:33

answered Jan 24, 2017 at 0:20

Fan Jin

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