//hide
document.getElementById('button-name').style.visibility = 'hidden';
//reveal
document.getElementById('button-name').style.visibility = 'visible';
let btnName = document.getElementById('btnId');
btnName.addEventListener('click', ()=>{
let element = document.getElementById('elementId');
if (element.style.display != 'inline'){
element.style.display = 'inline';
}
else{
element.style.display = 'none'
}
})