Any data structure with key, value but key not unique?

[torrent]

Hi,
I am looking for a data structure with key and value (Map or Dictionary) but key is not unique in Node-Red.
I have tried with this

var map1 = new Map();
map1.set("test", "value");

but it doesn't work at all.

[knolleary]

Hi @torrent

can you explain a bit more what you mean?

Do you mean you want to have multiple values for a single key?

The code you've shared is perfectly valid JavaScript. What do you mean it doesn't work at all? What do you want it to do?

[torrent]

Hi,
You are right. I want multiple values for a single key.
The code I've shared doesn't work when I run with debug (return msg already). It doesn't print anything out! msg is empty!

[knolleary]

There is no native JavaScript data structure that does that, but it is easy enough to do with a plain object where you ensure its values are arrays that contain 1 or more elements:

let map = {};
let key = "test";
let value = "value";

// Ensure that map[key] is an array if not already defined
map[key] = map[key] || [];
// Append the value to the array held in map[key]
map[key].push(value);