JSFiddle - React, Tailwind, and code Playground

JavaScript

var users = [{ "name":"John", "age":30, "car":"fiat" },{ "name":"Raj", "age":28, "car":"hundai" }];

var allUser =[]

for (var i = 0; i < users.length; i++) {
  test(i, users[i])
}
console.log(allUser);

function test(i, user) {
  allUser[i] = {
  username: user.name,
  userage: user.age
  }
}