Transform data from an nested array to an object

Question

I'm trying to turn this:

 var pets = [
        [
            ['dog', 'Harry'], ['age', 2]
        ],
        [
            ['dog', 'Roger'], ['age', 5]
        ]
    ]

into this:

var dogs = [
    {dog: 'Harry', age: 2},
    {dog: 'Roger', age: 5}
    ]

I keep on getting stuck. Here's what I've done so far. Any pointers toward the right direction would be greatly appreciated. Any suggestions on making it more readable would be helpful for me in the future too. Thanks

function arrayToObj(arr) {
  var newArray = [];
  for (var i = 0; i < arr.length; i++) {
    var obj = {};
    for (var j = 0; j < arr[i].length; j++) {
      var key = arr[i][j][0];
      obj[key] = key;
    }
    newArray[i] = obj;
  }
  return newArray; 
}

Possible duplicate of How to convert nested array pairs to objects in an array — Chetan
– Chetan, Commented Nov 16, 2016 at 7:00

Pranav C Balan · Accepted Answer · 2016-11-16 07:18:36Z

You can use Array#map and Array#reduce methods.

var pets = [
  [
    ['dog', 'Harry'],
    ['age', 2]
  ],
  [
    ['dog', 'Roger'],
    ['age', 5]
  ]
];


var dogs = pets.map(function(v) { // iterate over the array
  return v.reduce(function(obj, arr) { // iterate over inner array to generate object
    obj[arr[0]] = arr[1]; // define object property based on inner array element
    return obj; // return updated object 
  }, {}); // set initial value as an empty object
})

console.log(dogs);

FYI : If you would like to stick with your own code then you need to update the line obj[key] = key; with obj[key] = arr[i][j][1]; or there is no need of key variable at all simple use single line of code as obj[arr[i][j][0]] = arr[i][j][1];.

var pets = [
  [
    ['dog', 'Harry'],
    ['age', 2]
  ],
  [
    ['dog', 'Roger'],
    ['age', 5]
  ]
];

function arrayToObj(arr) {
  var newArray = [];
  for (var i = 0; i < arr.length; i++) {
    var obj = {};
    for (var j = 0; j < arr[i].length; j++) {
      obj[arr[i][j][0]] = arr[i][j][1];
      // updated here ------^^^^^^^----
    }
    newArray[i] = obj;
  }
  return newArray;
}

var dogs = arrayToObj(pets);

console.log(dogs);

Deepak Jose · Accepted Answer · 2016-11-16 07:03:16Z

1

function arrayToObj(arr) {
  return arr.map((item) => {
     var object = {};
     item.forEach((data) => {
       object[data[0]] = data[1];
     })
     return object
  })
}

answered Nov 16, 2016 at 7:03

Deepak Jose

766 bronze badges

Comments

fafl · Accepted Answer · 2017-04-18 08:06:17Z

1

This is something the Map constructor can do automatically for you:

var dogs = pets.map(pairs => new Map(pairs))

edited Apr 18, 2017 at 8:06

answered Nov 16, 2016 at 7:00

fafl

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Comments

Mike S. · Accepted Answer · 2016-11-16 07:04:25Z

0

 var pets = [
    [
        ['dog', 'Harry'], ['age', 2]
    ],
    [
        ['dog', 'Roger'], ['age', 5]
    ]
]



var petArr = pets.reduce(function(a, b) {
  var obj = {}
  b.forEach(function(set){
    obj[set[0]] = set[1]
  })
  return a.concat(obj)
}, [])

console.log(petArr)

answered Nov 16, 2016 at 7:04

Mike S.

9515 silver badges14 bronze badges

Comments

Mahi · Accepted Answer · 2016-11-16 07:05:55Z

0

change obj[key] = arr[i][j][1]; instead of obj[key] = key

i could have done with map and others array method but i want to show where you were wrong .

var pets = [
        [
            ['dog', 'Harry'], ['age', 2]
        ],
        [
            ['dog', 'Roger'], ['age', 5]
        ]
    ];
var a=function arrayToObj(arr) {
  var newArray = [];
  for (var i = 0; i < arr.length; i++) {
    var obj = {};
    for (var j = 0; j < arr[i].length; j++) {
      var key = arr[i][j][0];
      obj[key] = arr[i][j][1]; // change here instead of key 
    }
    newArray[i] = obj;
  }
  return newArray; 
}
console.log(a(pets));

answered Nov 16, 2016 at 7:05

Mahi

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Comments

Khanjan Bhatt · Accepted Answer · 2016-11-16 07:13:58Z

0

I hope following script will help you.

function arrayToObj(arr) {
        var newArray = [];
        for (var i = 0; i < arr.length; i++) {
            var obj = {
                dog: '',
                age: ''
            };

            obj.dog = arr[i][0][1];
            obj.age = arr[i][1][1];
            newArray.push(obj);
        }
        return newArray;
    }

answered Nov 16, 2016 at 7:13

Khanjan Bhatt

9410 bronze badges

Comments

Poiz · Accepted Answer · 2016-11-16 07:44:51Z

0

You could use a simple for() Loop nested within a forEach() Loop to get the Result you desire. QUICK-TEST HERE

var pets = [
  [
    ['dog', 'Harry'],
    ['age', 2]
  ],
  [
    ['dog', 'Roger'],
    ['age', 5]
  ]
];

function arrayToObject(arrData) {
  var objData = [];
  arrData.forEach(function(data, index) {
    var tmpObject = {};
    for (var i = 0; i < data.length; i++) {
      var arr = data[i];
      tmpObject[arr[0]] = arr[1];
    }
    objData.push(tmpObject);
  });
  return objData;
}

console.log( arrayToObject(pets) );

    // YIELDS::
        Array[2]
            0: Object
                age: 2
                dog: "Harry"
            1: Object
                age: 5
                dog: "Roger"

</script>

edited Nov 16, 2016 at 7:44

answered Nov 16, 2016 at 7:17

Poiz

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Comments

Pranav C Balan · Accepted Answer · 2016-11-16 08:17:24Z

0

You could assign the values as properties to the array, set array length to zero and convert the array type to a plain object, and assign it to the same element.

var pets = [[['dog', 'Harry'], ['age', 2]], [['dog', 'Roger'], ['age', 5]]];

pets.forEach(function (a, i, aa) {
    a.forEach(function (b, _, bb) {
        bb[b[0]] = b[1];
    });
    a.length = 0;
    aa[i] = Object.assign({}, aa[i]);
});

console.log(pets);

edited Nov 16, 2016 at 8:17

Pranav C Balan

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answered Nov 16, 2016 at 7:53

Nina Scholz

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