Vanilla Javascript Check for Class on Element

Sometimes, devs can rely on jquery a little too much, and forget how to check for a className without a framework to help. Granted
is easy. But sometimes, one must go jquery free!
However, the .contains is not supported by all browsers
So, you can always fallback to good oleindexOf
function hasClass(el, className) {
    return (' ' + el.className + ' ').indexOf(' ' + className+ ' ') > -1;