rithmschool / javascript_iterators

Supplementary JavaScript Iterators exercises

JavaScript Iterators

This repository consists of additional questions on several JavaScript iterators: forEach, map, filter, and reduce. If you need a refresher on these methods, check out our free course materials.

The problems all assume you have access to the song data in the data.js file. The data represents all of the songs to hit #1 on the Billboard Hot 100 from 2000 through 2015. The following data is recorded for each song:

• song name,
• artist name,
• the year when the song first hit #1
• the month when the song first hit #1
• the date in the month when the song first hit #1
• how many (not necessary consecutive!) weeks the song was #1
• the duration of the song, in minutes and seconds.

To use the data, throw it into the Chrome console, or use a tool like JSBin or Repl.it to copy and paste the data before you start trying to solve these problems.

Have fun!

forEach

1. Write a function called listNames which takes in an array of songs and console.logs the name of each one.
2. Write a function called listSongDetails which takes in an array of songs and console.logs details about each one. The details should be in the following example format: "Smooth, by Santana featuring Rob Thomas (4:00)".
3. Write a function called summerJamCount which takes in an array of songs and returns the number of songs which hit #1 on the charts in June, July, or August.

map

1. Write a function called getDurations which takes in an array of songs and returns an array of each song's duration.
2. Write a function called getDurationInSeconds which takes in an array of songs and returns an array of each song's duration in seconds.
3. Write a function called getMainArtists which takes in an array of songs and returns an array of the primary artists on the recordings. If there's only one artist, that artist should be returned; if there are featured artists, they should be ignored (so only the artist to the left of "featuring" is kept.)

filter

1. Write a function called getBigHits which takes an array of songs and returns an array of song objects which were number one for 10 or more weeks.
2. Write a function called getShortSongs which takes an array of songs and returns an array of songs which are shorter than 3 minutes.
3. Write a function called getSongsByArtist which takes in an array of songs and the name of an artist and returns an array of songs by that artist.

reduce

1. Refactor summerJamCount to use reduce!
2. Write a function called getTotalDurationInSeconds which takes in an array of songs and returns the total amount of time (in seconds) it would take to listen to all of the songs. (Hint: can you use anything you've written already to help solve this problem?)
3. Write a function called getSongCountByArtist which takes in an array of songs and returns an object. The keys in the object should be artist names, and the values should be the number of songs by that artist in the orignal array.
4. Write a function called averageWeeksAtNumberOne which takes in an array of songs and returns the average number of weeks that songs on the list were #1.