javascript merge two arrays with custom key

Question

I have two array with custom key but when i want to merge them JavaScript return emtpy array.

let x = [];
x['a'] = 1;

let y = [];
y['b'] = 2;

console.log(x.concat(y));
console.log([...x, ...y]);

There is any way to use JavaScript function two merge them or i have to use for and iterate all items??

let y = []; y['b'] = 2 results in an array with a property with the key 'b' and the value 2. concat and ... only consider properties with integral keys. Please explain what you are trying to accomplish as I doubt you are using the correct data structures. — Aluan Haddad
– Aluan Haddad, Commented Jul 16, 2020 at 5:18
@AluanHaddad Thank you for your comment. I understand that i should use Object for my case when i read your notice. — Mahdi Aslami Khavari
– Mahdi Aslami Khavari, Commented Jul 16, 2020 at 5:37

Siva Kondapi Venkata · Accepted Answer · 2020-07-16 05:19:22Z

4

Since you are using arrays like Object, use Object.keys. (Object.values and Object.entries)

let x = [];
x['a'] = 1;

let y = [];
y['b'] = 2;

console.log(x.concat(y));
console.log([...x, ...y]);

console.log([...Object.keys(x), ...Object.keys(y)]);
console.log([...Object.values(x), ...Object.values(y)]);

answered Jul 16, 2020 at 5:19

Siva Kondapi Venkata

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Md Mredul Jaman · Accepted Answer · 2020-07-16 05:21:39Z

2

Here you use string value as an array key. Which is not allowed in JavaScript. If you want string as a key you need to use 'object' instead of array.

answered Jul 16, 2020 at 5:21

Md Mredul Jaman

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1 Comment

Aluan Haddad Over a year ago

Not to be pedantic, but it absolutely is allowed they just aren't considered elements of the array, rather they are treated like length. It is usually best avoided however.

Ehsan Sepehri · Accepted Answer · 2020-07-16 05:31:35Z

0

If you want to merge this with using object try this:

let x = [{}];
x[0]['a'] = 1;

let y = [{}];
y[0]['b'] = 2;

console.log(x.concat(y));

answered Jul 16, 2020 at 5:31

Ehsan Sepehri

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