alert without jquery

js/src/dom/eventHandler.js

@@ -0,0 +1,40 @@
+/**
+ * --------------------------------------------------------------------------
+ * Bootstrap (v4.0.0-beta): dom/eventHandler.js
+ * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
+ * --------------------------------------------------------------------------
+ */
+
+const EventHandler = {
+  on(element, event, handler) {
+    if (typeof event !== 'string' || typeof element === 'undefined') {
+      return
+    }
+    element.addEventListener(event, handler, false)
+  },
+
+  one(element, event, handler) {
+    const complete = () => {
+      /* eslint func-style: off */
+      handler()
+      element.removeEventListener(event, complete, false)
+    }
+    EventHandler.on(element, event, complete)
+  },
+
+  trigger(element, event) {
+    if (typeof event !== 'string' || typeof element === 'undefined') {
+      return null
+    }
+
+    const eventToDispatch = new CustomEvent(event, {
+      bubbles: true,
+      cancelable: true
+    })
+    element.dispatchEvent(eventToDispatch)
+
+    return eventToDispatch
+  }
+}
+
+export default EventHandler