web audio xylophone

xylophone.js

function createXylophone() { 

    const context = new (window.AudioContext || window.webkitAudioContext)()
    const oscillator = context.createOscillator()
    const gain = context.createGain()
    oscillator.type = 'sine'
    oscillator.connect(gain)
    gain.connect(context.destination)

    return {
        context,
        oscillator,
        gain
    }
}

function playNote(frequency) {

    const { context, oscillator, gain } = createXylophone()
    const { currentTime } = context 

    oscillator.frequency.value = frequency

    gain.gain.setValueAtTime(0, currentTime)
    gain.gain.linearRampToValueAtTime(1, currentTime + 0.01)
    oscillator.start(currentTime)
    gain.gain.exponentialRampToValueAtTime(0.001, currentTime + 1)
    oscillator.stop(currentTime + 1)
}

playNote(493.88)