How to merge object inside object

Question

I have an array

  var input = [["group1","group2","group3" ], ["group1", "group5" ]]

I would like to merge two objects like this :

  ["group1","group2","group3", "group1", "group5" ]

I tried to merge two objects in one array, however, I couldn't get the answer. Any help would be appreciated.

No, you don't: you want to concatenate arrays, not merge objects. To concatenate arrays, there is the built in [concat](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat) function. — Mike 'Pomax' Kamermans, Jan 14 '19 at 21:06

score 4 · Accepted Answer · answered Jan 14 '19 at 21:06

4

I'm not too familiar with js, but can't you concat two arrays with something like

var merged = input[0].concat(input[1]);

answered Jan 14 '19 at 21:06

Chris

2,254
8
22

1

This should work beautifully. Good answer. – hmiedema9 Jan 14 '19 at 21:06
It works ! thanks :) – Jane Jan 14 '19 at 21:13

score 2 · Answer 2 · answered Jan 14 '19 at 21:07

You can use concat() like so:

const input = [
  ["group1", "group2", "group3"],
  ["group1", "group5"]
];

const output = [].concat.apply([], input);

console.log(output);

Or alternatively, Array.prototype.flat():

const input = [
  ["group1", "group2", "group3"],
  ["group1", "group5"]
];

const output = input.flat(1);

console.log(output);

Or if that is "hard" data, and will not change, you could use an even simpler concat() operation:

const input = [
  ["group1", "group2", "group3"],
  ["group1", "group5"]
];

const output = input[0].concat(input[1]);

console.log(output);

score 1 · Answer 3 · answered Jan 14 '19 at 21:07

1

You can use the concat function to combine the arrays.

const resultArr = [];

input.forEach(curr => {
  resultArr.concat(curr);
});

answered Jan 14 '19 at 21:07

pengcheng95

292
4
13

score 0 · Answer 4 · answered Jan 14 '19 at 21:06

You're talking about 'flattening the array'...

const flatten = (array) => {
  return array.reduce((flat, toFlatten) => {
    return flat.concat(Array.isArray(toFlatten) ? flatten(toFlatten) : toFlatten);
  }, []);
}
console.log(flatten([[1,2,[3]],4]));

score 0 · Answer 5 · answered Jan 14 '19 at 21:07

0

ES5

array.reduce(function(a, x) { return a.concat(x); }, []);

ES6

array.reduce((a, x) => a.concat(x), []);

answered Jan 14 '19 at 21:07

Đinh Carabus

3,403
4
22
44

score 0 · Answer 6 · answered Jan 14 '19 at 21:09

There is multiple approaches that you could take, my favorite would be to use the reduce method to transform your bi-dimensional array into one flat array and it would look like this :

function reducer(final_flat_array, inputItem) {
    return [...final_flat_array, ...inputItem]
};
let flat_array = input.reduce(reducer, []);

or a more 'imperative' way I guess :

let flat_array = [];
input.forEach(item => flat_array.push(item);

How to merge object inside object

6 Answers6