async function register() {
    if (document.getElementById('pass').value.length < 10) {
        alert('Password has to be at least 10 characters long')
        return
    }
    if (document.getElementById('user').value.length > 25) {
        alert('Username is too long!')
        return
    }
    if (document.getElementById('user').value.search('@') !== -1) {
        alert("User cannot contain '@' character!")
        return
    }
    let r = await post('/register', {
        user: document.getElementById('user').value,
        pass: document.getElementById('pass').value,
        r: REDIRECT_URL,
    })
    if (
        !r.url.endsWith('/user?success=true') &&
        !r.url.endsWith(REDIRECT_URL)
    ) {
        if (r.url.endsWith('already_exists')) {
            alert(
                'An account with that name already exists! Did you mean to login?'
            )
            return
        }
        //fallback
        document.getElementById('pass').value = ''
        console.error('registration failed')
        alert('Registration failed')
        return
    }
    window.location = REDIRECT_URL || '/user'
}

function passkeydown(e) {
    if (e.code === 'Enter') {
        register()
    }
}