Callback Example

1.js

console.log('Start') // Will execute first

setTimeout(1000, function thisWillHappenLater () {
  console.log('After Timeout') // Will execute third (after 1 second)
})

console.log('Keep going')  // Will execute second

2-d3-example.js

console.log('Start') // Will execute first

d3.csv("movies.csv", function thisWillHappenLater () {
  console.log('After Timeout') // Will execute third (after 1 second)
})

console.log('Keep going') // Will execute second

3-d3-example.js

console.log('Start') // Will execute first

var callback = function () {
  console.log('After Timeout') // Will execute third (after 1 second)
}

d3.csv("movies.csv", callback)

console.log('Keep going') // Will execute second