chore: Remove unnecessary methods and polyfills (#5614)

app/javascript/sdk/DOMHelpers.js

@@ -3,68 +3,20 @@ import { IFrameHelper } from './IFrameHelper';
 
 export const loadCSS = () => {
   const css = document.createElement('style');
-  css.type = 'text/css';
   css.innerHTML = `${SDK_CSS}`;
   document.body.appendChild(css);
 };
 
-export const wootOn = (elm, event, fn) => {
-  if (document.addEventListener) {
-    elm.addEventListener(event, fn, false);
-  } else if (document.attachEvent) {
-    // <= IE 8 loses scope so need to apply, we add this to object so we
-    // can detach later (can't detach anonymous functions)
-    // eslint-disable-next-line
-    elm[event + fn] = function() {
-      // eslint-disable-next-line
-      return fn.apply(elm, arguments);
-    };
-    elm.attachEvent(`on${event}`, elm[event + fn]);
-  }
-};
-
-export const classHelper = (classes, action, elm) => {
-  let search;
-  let replace;
-  let i;
-  let has = false;
-  if (classes) {
-    // Trim any whitespace
-    const classarray = classes.split(/\s+/);
-    for (i = 0; i < classarray.length; i += 1) {
-      search = new RegExp(`\\b${classarray[i]}\\b`, 'g');
-      replace = new RegExp(` *${classarray[i]}\\b`, 'g');
-      if (action === 'remove') {
-        // eslint-disable-next-line
-        elm.className = elm.className.replace(replace, '');
-      } else if (action === 'toggle') {
-        // eslint-disable-next-line
-        elm.className = elm.className.match(search)
-          ? elm.className.replace(replace, '')
-          : `${elm.className} ${classarray[i]}`;
-      } else if (action === 'has') {
-        if (elm.className.match(search)) {
-          has = true;
-          break;
-        }
-      }
-    }
-  }
-  return has;
-};
-
-export const addClass = (elm, classes) => {
-  if (classes) {
-    elm.className += ` ${classes}`;
-  }
+export const addClasses = (elm, classes) => {
+  elm.classList.add(...classes.split(' '));
 };
 
 export const toggleClass = (elm, classes) => {
-  classHelper(classes, 'toggle', elm);
+  elm.classList.toggle(classes);
 };
 
-export const removeClass = (elm, classes) => {
-  classHelper(classes, 'remove', elm);
+export const removeClasses = (elm, classes) => {
+  elm.classList.remove(...classes.split(' '));
 };
 
 export const onLocationChange = ({ referrerURL, referrerHost }) => {