Mapping two arrays to create one array

November 11, 2021

I have two arrays which id like to merge into one array, however, the arrays have some complexities which I can’t wrap my head around…. In short, I have an array of "last message" from a conversation, and I have an array of participants from that conversation.

The "messages" array looks like this

messageArray =
[
  [
    { message } <=== convo 1
  ],
  [
    { message } <===  convo 2
  ],
]

The "participant" data array looks like this

participantArray = 
[
   [
     {participant},{participant} <=== participants in convo 1
   ],
   [
     {participant},{participant},{participant} <=== participants in convo 2
   ]
]

What i’d like to have is

mergedArray =
[
  [ { message }, [ { participant }, { participant  } ]] <=== conversation 1
],
[
  [ { message }, [ { participant }, { participant  } ]] <=== conversation 2
]

>Solution :

Based on your description, you can map the first array, and use the index to get the associated items in the second array.

eg.

const messages = [
  ["Helo World, Messsage One"],
  ["Goodbye, fair well"],
];

const users = [
   ["Bob", "Jane", "Harry"],
   ["Mike", "John", "Amanda"]
];

const joined = messages.map((m, ix) => {
  return [m[0], users[ix]];
});

console.log(joined);