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// Helpers
function appendElement(parentElement, tag) {
element = document.createElement(tag)
parentElement.appendChild(element)
return element
}
function appendText(parentElement, text) {
element = document.createTextNode(text)
parentElement.appendChild(element)
return element
}
// Select tonality
tonalities_b = ['C', 'D♭', 'D', 'E♭', 'E', 'F', 'G♭', 'G', 'A♭', 'A', 'B♭', 'B']
tonalities_s = ['C', 'C♯', 'D', 'D♯', 'E', 'F', 'F♯', 'G', 'G♯', 'A', 'A♯', 'B']
function getRoot(c) {
if (c.indexOf('♯') > -1 || c.indexOf('♭') > -1) {
return c.substring(0, 2)
} else {
return c[0]
}
}
function getShift(t1, t2) {
return tonalities_b.indexOf(getRoot(t2)) - tonalities_b.indexOf(getRoot(t1))
}
function applyShift(tonalities, t1, s) {
const xs = t1.split('/')
if (xs.length > 1) {
return `${applyShiftChord(tonalities, xs[0], s)}/${applyShiftChord(tonalities, xs[1], s)}`
} else {
return applyShiftChord(tonalities, t1, s)
}
}
function applyShiftChord(tonalities, t1, s) {
let root = getRoot(t1)
const mode = t1.substring(root.length)
const index = tonalities_b.indexOf(root) > -1 ? tonalities_b.indexOf(root) : tonalities_s.indexOf(root)
root = tonalities[(index + s + tonalities.length) % tonalities.length]
return `${root}${mode}`
}
const node = document.getElementById('g-Tonality')
if (node !== null) {
let tonality = node.innerText
mode = tonality[tonality.length - 1] == 'ₘ' ? 'ₘ' : ''
select = document.createElement('select')
select['name'] = 'tonality'
tonalities_b.forEach(t => {
option = appendElement(select, 'option')
option['value'] = t
if (tonality == `${t}${mode}`) {
option['selected'] = true
}
appendText(option, `${t}${mode}`)
})
select.onchange = (e) => {
const shift = getShift(tonality, e.target.value)
tonality = e.target.value
tonalities = tonality === 'F' || tonality.indexOf('♭') > -1 ? tonalities_b : tonalities_s
document.querySelectorAll('.g-Chords__Name').forEach(chord => {
if (chord.innerText !== '%') {
chord.innerText = applyShift(tonalities, chord.innerText, shift)
}
})
}
node.parentNode.replaceChild(select, node)
}
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