I have a form that I need to calculate the difference in minutes between the current date and time and the user selected (future) date and time, but it doesn't seem to work:

form.addEventListener('submit', function (e) {
    e.preventDefault()
    currentDate.value = new Date().toLocaleString()
    delay.value = toMinutes((Date.parse(scheduled.value) - Date.now())/1000)
    localStorage.message = '{"recip": "' + recip.textContent + '", "msg": "' + msg.value + '", "sender": "' + sender.textContent + '"}'
    this.submit()
})

FYI: I'm a newbie here and newbie to javascript so apologies if i haven't provided enough info.