How can assign multiple css classes to an html element through javascript without using any libraries?
Here's a simpler method to add multiple classes via classList
(supported by all modern browsers, as noted in other answers here):
div.classList.add('foo', 'bar'); // add multiple classes
From: https://developer.mozilla.org/en-US/docs/Web/API/Element/classList#Examples
If you have an array of class names to add to an element, you can use the ES6 spread operator to pass them all into classList.add()
via this one-liner:
let classesToAdd = [ 'foo', 'bar', 'baz' ];
div.classList.add(...classesToAdd);
Note that not all browsers support ES6 natively yet, so as with any other ES6 answer you'll probably want to use a transpiler like Babel, or just stick with ES5 and use a solution like @LayZee's above.