html set attribut code example
Example 1: javascript setattribute
element.setAttribute(<name>, <value>);
// ex
var aElement = document.querySelector("a");
aElement.setAttribute("href", "https://isitchristmas.com/");
// same as <a href="https://isitchristmas.com/"></a>
Example 2: set property dom javascrpt
document.getElementsByTagName("H1")[0].setAttribute("class", "democlass");