Slash chords with the bass

[dok]

Hey @danigb, I was wondering if you'd like help implementing this. Is there a particular structure that you are thinking about when a user passes in something like:

const Chord = require("@tonaljs/chord");

Chord.get('G/C')

/**
{ empty: false,
  name: 'G major',
  setNum: 2192,
  chroma: '100010010000',
  normalized: '100001000100',
  intervals: [ '1P', '3M', '5P' ],
  quality: 'Major',
  aliases: [ 'M', '' ],
  symbol: 'G',
  type: 'major',
  root: '',
  rootDegree: 0,
  tonic: 'G',
  notes: [ 'G', 'B', 'D' ] }
**/

What would be the ideal scenario here? How about something like:

{ empty: false,
  name: 'G major',
  setNum: 2192,
  chroma: '100010010000',
  normalized: '100001000100',
  intervals: [ '4P', '1P', '3M', '5P' ],
  quality: 'Major',
  aliases: [ 'M', '' ],
  symbol: 'G',
  type: 'major',
  root: 'C',
  rootDegree: 0,
  tonic: 'G',
  notes: ['C', 'G', 'B', 'D' ] }

Other references: #164

[danigb]

Hi @dok , yes! That would be awesome.

Sou you are thinking about adding a couple of fields, right? 👇

• root (string, "" by default)
• rootDegree (number 0 by default, means same as tonic)

I'm wondering if "bass" instead of "root" is a better word? Looks like wikipedia uses that term: https://en.wikipedia.org/wiki/Slash_chord

Things to consider:

• What happens if the root/bass is not part of the chord? (Without going deep, I think it should return an empty not valid chord)
• What happens if the root/bass is not a note?

[dok]

Adding "bass" in conjunction with the "root" property sounds good! It would be better than manipulating the root, since we won't lose information about the chord. In that case, I don't think the rootDegree would change either.

What happens if the root/bass is not part of the chord? (Without going deep, I think it should return an empty not valid chord)

I think that sounds good for now

What happens if the root/bass is not a note?

That would be like if someone specified a "Eb/Eb" 😂. I think we can either treat it as an "Eb" or return a non-valid chord. What do you think?

[stevage]

Chiming in here. No idea if this will get implemented, but my thoughts:

• add a bass attribute that for C would be C and for C/Bb would be Bb.
• name should reflect the slash, maybe C major over Bb
• aliases should contain the slash

Harder questions:

• for type, should every type/slash combo be considered unique (ie, is the type of C/Bb "major over flat seventh" or is it just "major slash")
• does intervals include the bass note? I guess it does, but for some applications that may not be expected.

(I didn't really understand the "Without going deep, I think it should return an empty not valid chord" comment. Maybe you are thinking mostly of classical music where the slash chord indicates an inversion, whereas I'm mostly thinking of jazz/pop, where it most often is a non-chord tone).