Javascript - convert array of arrays into array of objects with prefilled values

Question

I have following array:

[
    [val1, val2]
    [val1, val2]
    [val1, val2]
    [valN, valN]
]

N represents the fact that these arrays are not limited, i.e I never know how much of them do I store. What I try to accomplish is converting that array to array of objects with keys lat and lng and I expect so have final result as following so I can use it for further needs:

[
    {
        lat: val1,
        lng: val2
    },
    {
        lat: val1,
        lng: val2
    },
    {
        lat: valN,
        lng: valN
    }
]

I found a function to convert these inner arrays to objects and it looks like this:

objectify(array) {
    return array.reduce(function(result, currentArray) {
        result[currentArray[0]] = currentArray[1];
        return result;
    }, {});
}

It works but output looks like this:

[
    {val1: val1, val2: val2}
    {val1: val1, val2: val2}
    {valN: valN, valN: valN}
]

and that's not what I'm looking for, because I really need these lat and lng to be keys of an object. How can I solve such issue?

Mike 'Pomax' Kamermans · Accepted Answer · 2022-02-17 16:50:42Z

24

You can simply use Array.prototype.map to project an array into another one by applying a projection function:

var arrs = [
    [1, 2],
    [3, 4],
    [5, 6],
    [7, 8]
];

var objs = arrs.map(x => ({ 
  lat: x[0], 
  lng: x[1] 
}));

/* or, using the older "function" syntax:

var objs = arrs.map(function(x) { 
  return {
    lat: x[0], 
    lng: x[1] 
  };
);

*/

console.log(objs);

edited Feb 17, 2022 at 16:50

Mike 'Pomax' Kamermans

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answered Jul 19, 2017 at 9:18

Yeldar Kurmangaliyev

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1 Comment

Michael Spiegelberg Over a year ago

Thank you Yeldar, it worked perfecly fine for me! I will accept it as answer in about 5 minutes in case your post was the first one to come.

str · Accepted Answer · 2017-07-19 09:38:12Z

15

Using ES6 you can write this in a very concise way:

var arrs = [
    [1, 2],
    [3, 4],
    [5, 6],
    [7, 8]
];
const locations = arrs.map(([lat, lng]) => ({lat, lng}));
console.log(locations);

edited Jul 19, 2017 at 9:38

answered Jul 19, 2017 at 9:26

str

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5 Comments

Fazeel Qureshi Over a year ago

how can I make it like this? [ { 1 : 2 } , { 3 : 4 } , { 5 : 6 } , { 7 : 8 } ]

str Over a year ago

@fazeelzama Replace {lat, lng} with {[lat]: lng}.

VersifiXion Over a year ago

i need to do same thing but i have arrs.map is not a function

str Over a year ago

@Versifiction You should ask a new question and provide details with actual code. There is absolutely no way to know what you're doing with just that comment alone.

VersifiXion Over a year ago

here's my topic stackoverflow.com/questions/60999060/…

abhishekkannojia · Accepted Answer · 2017-07-19 09:20:14Z

1

You can use Array#map to achieve this. Array#map passes each array element through a projection function and returns the values in a new array.

var data= [
    ['val1', 'val2'],
    ['val1', 'val2'],
    ['val1', 'val2'],
    ['valN', 'valN'],
];

var result = data.map(function(row) {
  return {
    lat: row[0],
    lng: row[1]
  };
});

console.log(result);

answered Jul 19, 2017 at 9:20

abhishekkannojia

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1 Comment

VersifiXion Over a year ago

i need to do same thing but i have data.map is not a function

Jay · Accepted Answer · 2017-07-19 09:21:05Z

0

var array = [
    ['val1', 'val2'],
    ['val1', 'val2'],
    ['val1', 'val2'],
    ['valN', 'valN']
];

var arrayObject = array.map(function(item){ 
  return { lat: item[0], lng: item[1]};
});

console.log(arrayObject);

answered Jul 19, 2017 at 9:21

Jay

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1 Comment

VersifiXion Over a year ago

i need to do same thing but i have array.map is not a function

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