DOM Manipulating Attributes Setting an attribute
Example
Some attributes are directly accessible as properties of the element (e.g. alt, href, id, title and value).
document.querySelector("a").href = "#top";
Other attributes, including data-attributes can be set as follows:
document.querySelector("a").setAttribute("aria-label", "I like turtles");
Data attributes can also be set using dataset (modern browsers)
var a = document.querySelector("a");
a.dataset.test = "123";
a.dataset['test-2'] = "456";
results in
<a href="#" data-test="123" data-test-2="456">Widget</a>
