CODEWITHSUNDEEP
javascriptarraysobjectfilterforeach
forestkelley
forestkelley

Reputation: 341

Filter array of objects against another array of objects. Remove items with array values that matches those inside another array of objects

I've used .filter successfully in the past, but I can't figure out this use case.

I want to return a clone of the array chordLibrary (presumably using .filter). But I want to remove any items/objects from this new array where any array value of the property name notesInChord happens to match any of the array values of badNotes.keyIndex.

To clarify, I will compare each item in chordLibrary against every item in badNotes and remove an item from chordLibrary if its array values matches any of the array values in any of the items items in badNotes.

In the following example, you can see that the first item in chordLibrary includes the array value 5, and so that item is removed in the result.

const chordLibrary = [
    { notesInChord: [5, 8], chordName: 'Major' },
    { notesInChord: [4, 8], chordName: 'Minor' },
    { notesInChord: [8], chordName: '5' }
];
const badNotes = [
    {"keyIndex":[1],"keyName":"C#"},
    {"keyIndex":[3],"keyName":"D#"},
    {"keyIndex":[5],"keyName":"E"}
];

// example result: "
const newChordLibrary = [
    { notesInChord: [4, 8], chordName: 'Minor' },
    { notesInChord: [8], chordName: '5' }
];

I assume I need to nest or use a for loop or forEach to do this, but I can't figure it out.

ES6 solutions are ok.

Thanks!

Upvotes: 0

Views: 41

Answers (1)

Majed Badawi
Majed Badawi

Reputation: 28424

In the filter you can use a custom method that searches in the notesInChord if any of them are found in badNotes using find as follows:

const chordLibrary = [
    { notesInChord: [5, 8], chordName: 'Major' },
    { notesInChord: [4, 8], chordName: 'Minor' },
    { notesInChord: [8], chordName: '5' }
];
const badNotes = [
    {"keyIndex":[1],"keyName":"C#"},
    {"keyIndex":[3],"keyName":"D#"},
    {"keyIndex":[5],"keyName":"E"}
];

function getGoodNotes(chordList){
     return chordList.filter((chord)=>{
          if(!containsBadNote(chord.notesInChord))
               return chord;
     });
}
function containsBadNote(notesInChord){
     for(let i = 0; i < notesInChord.length; i++){
          var note = notesInChord[i];
          if(badNotes.find((n)=> n.keyIndex[0]==note)!=null)
               return true;
     }
     return false;
}

console.log( getGoodNotes(chordLibrary) );

Upvotes: 1

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