Element.setAttribute


Element.setAttribute()


Sets the value of an attribute on the specified element. If the attribute already exists, the value is updated; otherwise a new attribute is added with the specified name and value.
To get the current value of an attribute, use getAttribute() ; to remove an attribute, call removeAttribute() .
var b = document.querySelector("button");

b.setAttribute("name", "helloButton");
b.setAttribute("disabled", "");