I am currently reviewing JavaScript Closure. The cool thing about JavaScript closures is that the returned function has access to the variables declared in the outer function but only those variables that are used inside the return function. In the example below, we can see the return function is actually accessing two objects. First the index variable declared in the outer function. Secondly, which is being done sneakily, is the names array which was passed in as an argument to the outer function.

Write a function rollCall that accepts an array of names and returns a function. The first time the returned function is invoked, it should log the first name to the console. The second time it is invoked, it should log the second name to the console, and so on, until all names have been called. Once all names have been called, it should log ‘Everyone accounted for’.

function rollCall(names) {
  let index = 0
  let size = names.length - 1

  return function (){
    if (index <= size){
    } else {
      console.log(`Everyone accounted for`)

const rollCaller = rollCall(['Victoria', 'Juan', 'Ruth'])
rollCaller() // => should log 'Victoria'
rollCaller() // => should log 'Juan'
rollCaller() // => should log 'Ruth'
rollCaller() // => should log 'Everyone accounted for'

// output
'Everyone accounted for'