add attribute to button javascript code example

Example 1: javascript change attribute

var element = document.getElementById("elemId");
element.setAttribute("attributeName", "value");

Example 2: 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 3: put new attribute on html tag using javascript

// Here's what you do for the style attribute
span.setAttribute("style", "width:110%;float:center;left-margin:-10px;top-margin:-10;");