added prettier and eslint for dev

lib/domUtils.ts

@@ -0,0 +1,32 @@
+export const addGlobalEventListener = (
+  type: string,
+  selector: string,
+  callback: (arg0: Event) => void,
+  options: boolean | AddEventListenerOptions,
+  parent = document
+): void => {
+  parent.addEventListener(
+    type,
+    (e: Event) => {
+      if (e != null && e.target != null) {
+        const el = e.target as Element
+        if (el.matches(selector)) callback(e)
+      }
+    },
+    options
+  )
+}
+
+export const qs = (
+  selector: string | keyof HTMLElementTagNameMap,
+  parent = document
+): Element => {
+  return parent.querySelector(selector)
+}
+
+export const qsa = (
+  selector: string | keyof HTMLElementTagNameMap,
+  parent = document
+): Element[] => {
+  return [...parent.querySelectorAll(selector)]
+}