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 user_message_list = [];
    messages.map(function (message) {
    return users.
        filter(function (user) {
            return user.userId == message.userId
        }).
        map(function (user) {
            return {
                "userId": user.userId,
                "userName": user.userName,
                "msg": message.msg
            }
        })
})
.forEach(function (item) { // eliminate nested layers 
    user_message_list.push.apply(user_message_list, item)
})

console.log(user_message_list)