set attribute javascript

var element = document.getElementById("elemId");
element.setAttribute("attributeName", "value");element.setAttribute(<name>, <value>);
// ex
var aElement = document.querySelector("a"); 
aElement.setAttribute("href", "https://isitchristmas.com/"); 
// same as <a href="https://isitchristmas.com/"></a>Element.setAttribute(name, value);const link = document.querySelector('a');

console.log(link.getAttribute('href'));
link.setAttribute('href', 'https://yandex.ru');
link.innerText = 'The Next Link';

const mssg = document.querySelector('p');

console.log(mssg.getAttribute('class'));

mssg.setAttribute('class', 'success');
mssg.setAttribute('style', 'color: green;');document.getElementsByTagName("H1")[0].setAttribute("class", "democlass");