Object array clone with subset of properties

Question

What is the most efficient way in JavaScript to clone an array of uniform objects into one with a subset of properties for each object?

UPDATE

Would this be the most efficient way to do it or is there a better way? -

var source = [
    {
        id: 1,
        name: 'one',
        value: 12.34
    },
    {
        id: 2,
        name: 'two',
        value: 17.05
    }
];

// copy just 'id' and 'name', ignore 'value':
var dest = source.map(function (obj) {
    return {
        id: obj.id,
        name: obj.name
    };
});

possible duplicate of How to get a subset of a javascript object's properties — artm
– artm, Commented Jun 5, 2015 at 11:09
@artm, that question is about one object, while I'm asking about an array of objects. — vitaly-t
– vitaly-t, Commented Jun 5, 2015 at 11:13
Well, you could use stackoverflow.com/a/17781590/3309109 for example and call it for each object in your array. — artm
– artm, Commented Jun 5, 2015 at 11:16

Ivan Nosov · Accepted Answer · 2016-09-05 15:24:35Z

10

using Object Destructuring and Property Shorthand

let array = [{ a: 5, b: 6, c: 7 }, { a: 8, b: 9, c: 10 }];
let cloned = array.map(({ a, c }) => ({ a, c }));

console.log(cloned); // [{ a: 5, c: 7 }, { a: 8, c: 10 }]

answered Sep 5, 2016 at 15:24

Ivan Nosov

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Comments

Khalid · Accepted Answer · 2015-06-05 11:26:19Z

2

First define a function that clone an object and return a subset of properties,

Object.prototype.pick = function (props) {
   return  props.reduce((function (obj, property) {
        obj[property] = this[property];
        return obj;
   }).bind(this), {});
}

Then define a function that clone an array and return the subsets of each object

function  cloneArray (array, props) { 
    return array.map(function (obj) { 
       return obj.pick(props);
    });
}

Now let's say you have this array :

var array = [
   { name : 'khalid', city : 'ifrane', age : 99 },
   { name : 'Ahmed', city : 'Meknes', age : 30 }
];

you need to call the function and pass the array of properties you need to get as result

cloneArray(array, ['name', 'city']);

The result will be :

[
   { name : 'khalid', city : 'ifrane' },
   { name : 'Ahmed', city : 'Meknes' }
]

edited Jun 5, 2015 at 11:26

answered Jun 5, 2015 at 11:19

Khalid

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1 Comment

vitaly-t Over a year ago

That's even more generic an answer than I was looking for, i.e. I didn't mind specifying columns during the copy operation. Your answer is more reusable and clean. Thank you!

rrowland · Accepted Answer · 2015-06-05 11:25:35Z

1

Performance-wise, that would be the most efficient way to do it, yes.

answered Jun 5, 2015 at 11:25

rrowland

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1 Comment

vitaly-t Over a year ago

Thank you! I did an update after the first answer, which gives a very good and more generic approach.

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