button in vanilla js

var button = document.createElement('button');
button.setAttribute('class','etmkug-14 SuUwW');
button.setAttribute('style','margin-left: 10px;');
button.setAttribute('id','mark-all-read');
var span = document.createElement('span');
span.setAttribute('class','etmkug-16 ctwFJG');
span.innerHTML = 'Mark All Read';
button.appendChild(span);    
document.body.append(button);let newButton = document.createElement('button');
newButton.setAttribute("id", "myNewButton");
newButton.className = "myClassName";
newButton.innerText = "clickMe";
newButton.addEventListener("click", clickMe);
document.body.appendChild(newButton);
function clickMe(){
    console.log("Hi! I  am a new Button.");
}