Vanilla JS - Add Class / Remove Class / Has Class

gistfile1.js

function hasClass(ele,cls) {
  return ele.className.match(new RegExp('(\\s|^)'+cls+'(\\s|$)'));
}
 
function addClass(ele,cls) {  
  if (!hasClass(ele,cls)) ele.className += " "+cls;
}
 
function removeClass(ele,cls) {
  if (hasClass(ele,cls)) {      
    var reg = new RegExp('(\\s|^)'+cls+'(\\s|$)'); 
    ele.className=ele.className.replace(reg,' ');  
  }
}
 
 
// Example
 
var myElement = document.getElementById('foo');
 
addClass(myElement, 'foo-class');
removeClass(myElement, 'foo-class');
if (hasClass(myElement, 'foo-class')) {
	return true;
} else {
	return false
}