Why my solution doesnt work on Functional Programming - Use the reduce Method to Analyze Data

Tell us what’s happening:
why my solution doesnt work

let getRating = (watchList, directorName) => {

    let targetDirector = watchList.filter(x => x["Director"] ===  directorName);

  let num = targetDirector.map(k => Number(k["imdbRating"]))

  let total = num.reduce((currentTotal, item) => currentTotal + item)

  let totalAverageRating = total / targetDirector.length

  // Only change code above this line 

  return totalAverageRating;


console.log(getRating(watchList,'Christopher Nolan'))

even though the result is the same in the hint section

Your code so far


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Challenge: Use the reduce Method to Analyze Data

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It’s not working because you’ve changed how it works.

The purpose of the function is to return the average rating for “Christopher Nolan” films.

You have enhanced the function to allow it to search for any director. This is great: it makes it much more useful!

But your function will fail the tests, because the tests will run:


In your code, this line:

let targetDirector = watchList.filter(x => x["Director"] ===  directorName);

directorName wil be undefined. The result of that filter will therefore be []. There are no directors who are undefined.

To fix, either:

Remove the second parameter (directorName). Replace directorName in the filter with "Christopher Nolan":

let getRating = (watchList) => {
  let targetDirector = watchList.filter(x => x["Director"] ===  "Christopher Nolan");

In this case, hard-code the function to only search for Christopher Nolan films. Or…

Keep what you have. Pass a default value for the parameter:

let getRating = (watchList, directorName = "Christopher Nolan")  => {
  let targetDirector = watchList.filter(x => x["Director"] ===  directorName);

In this case, if directorName is undefined, then use the value "Christopher Nolan"