JSFiddle - React, Tailwind, and code Playground

by Jay Scott. ANDERSON

JavaScript

var users = [{ userName: 'vimal', userId: 789 },
    { userName: 'kabilan', userId: 456 },
    { userName: 'yathavan', userId: 123 }]

var messages = [ { userId: '123', msg: 'hi' },
    { userId: '789', msg: 'yth' },
    { userId: '789', msg: 'hu' } ]

var messages_users = []
var message_user = {}
for (ii=0; ii < messages.length; ii++) {
    message_user = {
        "userId": messages[ii].userId,
        "msg": messages[ii].msg
    }
    for (iii=0; iii < users.length; iii++) {
        if ( messages[ii].userId == users[iii].userId ) {
            message_user.userName = users[iii].userName
        }
    }
    messages_users.push(message_user)
}
console.log(messages_users)