Callback in Js

callback.js

getUser(1, user => {
  console.log('user', user)
  getRepo(user.githubUserName, (repo) => {
    console.log('Repos', repo)
})
})


function getUser(id, callback) {
  setTimeout(()=>{
    console.log('Reading A user From Database')
    callback({id: id, githubUserName: 'shohan'})
  },2000)
}

function getRepo(userName, callback) {
  setTimeout(() => {
  console.log("Calling Githum Api")
  callback(['repo1', 'repo2', 'repo3']) // we can't return directly here
  }, 2000)
}