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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
}
// Only suggest sharps for the moment
tonalities = ['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.indexOf(getRoot(t2)) - tonalities.indexOf(getRoot(t1))
}
function applyShift(t1, s) {
let root = getRoot(t1)
let mode = t1.substring(root.length)
root = tonalities[(tonalities.indexOf(root) + s + tonalities.length) % tonalities.length]
return `${root}${mode}`
}
const node = document.querySelector('[data-tonality]')
let tonality = node.dataset.tonality
mode = tonality[tonality.length - 1] == 'm' ? 'm' : ''
label = appendElement(node, 'label')
label['className'] = 'g-Chords__Tonality'
label.onchange = (e) => {
const shift = getShift(tonality, e.target.value)
tonality = e.target.value
document.querySelectorAll('.g-Chords__Chord').forEach(chord => {
if (chord.innerText !== '%') {
chord.innerText = applyShift(chord.innerText, shift)
}
})
}
appendText(label, 'Tonalité :')
select = appendElement(label, 'select')
select['name'] = 'tonality'
tonalities.forEach(t => {
option = appendElement(select, 'option')
option['value'] = t
if (tonality == `${t}${mode}`) {
option['selected'] = true
}
appendText(option, `${t}${mode}`)
})
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