Вот опция, которая позволит пользователю переключать числовые вводы вверх и вниз:
<input type="number" id="fraction-1"/>
<input type="number" id="fraction-2"/>
Current Signature:
<div id="current-sig"></div>
Затем в вашем javascript ...
// Get the select form element
const FRACT_1 = 'fract-1'
const FRACT_2 = 'fract-2'
const fract1 = document.querySelector(`#${FRACT_1}`)
const fract2 = document.querySelector(`#${FRACT_2}`)
const currentSigDiv = document.querySelector('#current-sig')
let currentSignature = '4/4'
const changeSignatureByFraction = ({target}) => {
if(target.id === FRACT_1)) {
currentSignature = `${target.value}${currentSignature.substring(1)}`
stave.addClef("treble").addTimeSignature(currentSignature)
currentSigDiv.innerHTML = currentSignature
} else {
currentSignature = `${currentSignature.slice(0, -1)}${target.value}`
stave.addClef("treble").addTimeSignature(currentSignature)
currentSigDiv.innerHTML = currentSignature
}
}
// Listen for a change event
fract1.addEventListener('change', changeSignatureByFraction)
fract2.addEventListener('change', changeSignatureByFraction)
currentSigDiv.innerHTML = currentSignature