javascript change attribute

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);