How To Transform An Array/dataset In Javascript?

Say I have an array of music The code below returns all the titles for all genres. However, I only want the title names for songs in the Country genre.

Solution 1:

.filter the array by whether Country is included in the genres, then .map to the titles:

const music=[{title:"Cheats",year:2018,cast:["Jane Rhee","Kacey Brown"],genres:["Country"]},{title:"Road",year:2018,cast:["Jeff Bates","Alan Walker","Cindy Bates"],genres:["Country"]},{title:"Trail Down",year:2018,cast:["Ken Clemont"],genres:["Jazz"]},{title:"Way Down",year:2018,cast:["Denzel Harr","Dan Smith","Lee Kyle","Nate Hill"],genres:["Pop"]},{title:"Fountain",year:2018,cast:["Brad Smith","Rosa King"],genres:["Rock"]},{title:"Gold Bells",year:2018,cast:["Paisley John"],genres:["Blues"]},{title:"Mountain Curve",year:2018,cast:["Michael Johnson"],genres:["Country"]},{title:"Arabella",year:2018,cast:[],genres:["Jazz"]},{title:"Curved",year:2018,cast:["Brett Shay"],genres:["Country"]}];
 
 const countryTitles = music
   .filter(({ genres }) => genres.includes('Country'))
   .map(({ title }) => title);
 console.log(countryTitles)

If you want to do it while only iterating over the dataset once, use reduce instead:

const music=[{title:"Cheats",year:2018,cast:["Jane Rhee","Kacey Brown"],genres:["Country"]},{title:"Road",year:2018,cast:["Jeff Bates","Alan Walker","Cindy Bates"],genres:["Country"]},{title:"Trail Down",year:2018,cast:["Ken Clemont"],genres:["Jazz"]},{title:"Way Down",year:2018,cast:["Denzel Harr","Dan Smith","Lee Kyle","Nate Hill"],genres:["Pop"]},{title:"Fountain",year:2018,cast:["Brad Smith","Rosa King"],genres:["Rock"]},{title:"Gold Bells",year:2018,cast:["Paisley John"],genres:["Blues"]},{title:"Mountain Curve",year:2018,cast:["Michael Johnson"],genres:["Country"]},{title:"Arabella",year:2018,cast:[],genres:["Jazz"]},{title:"Curved",year:2018,cast:["Brett Shay"],genres:["Country"]}];
 
const countryTitles = music
  .reduce((a, { genres, title }) => {
     if (genres.includes('Country')) {
       a.push(title)
     }
     return a;
   }, []);
console.log(countryTitles)

Solution 2:

Try this:

let songs = []; 

for (var i = 0; i < music.length; i++) {
    if(music[i].genres == "Country"){ // if music genres equal to "country"
        songs.push(music[i].title);
    }  
}

// output : Cheats,Road,Mountain Curve,Curved