chore: convert helpers.js to TypeScript (#1156)

package.json

@@ -65,6 +65,9 @@
       "plugin:import/typescript"
     ],
     "rules": {
+      "@typescript-eslint/prefer-optional-chain": "off",
+      "@typescript-eslint/no-explicit-any": "off",
+      "@typescript-eslint/no-unsafe-member-access": "off",
       "@typescript-eslint/prefer-includes": "off",
       "import/prefer-default-export": "off",
       "import/no-unassigned-import": "off",

src/helpers.js → src/helpers.ts

@@ -4,10 +4,11 @@ const TEXT_NODE = 3
 
 function jestFakeTimersAreEnabled() {
   /* istanbul ignore else */
+  // eslint-disable-next-line
   if (typeof jest !== 'undefined' && jest !== null) {
     return (
       // legacy timers
-      setTimeout._isMockFunction === true ||
+      (setTimeout as any)._isMockFunction === true ||
       // modern timers
       Object.prototype.hasOwnProperty.call(setTimeout, 'clock')
     )
@@ -23,7 +24,7 @@ function getDocument() {
   }
   return window.document
 }
-function getWindowFromNode(node) {
+function getWindowFromNode(node: any) {
   if (node.defaultView) {
     // node is document
     return node.defaultView
@@ -60,11 +61,11 @@ function getWindowFromNode(node) {
   }
 }
 
-function checkContainerType(container) {
+function checkContainerType(container: unknown) {
   if (
     !container ||
-    !(typeof container.querySelector === 'function') ||
-    !(typeof container.querySelectorAll === 'function')
+    !(typeof (container as any).querySelector === 'function') ||
+    !(typeof (container as any).querySelectorAll === 'function')
   ) {
     throw new TypeError(
       `Expected container to be an Element, a Document or a DocumentFragment but got ${getTypeName(
@@ -73,7 +74,7 @@ function checkContainerType(container) {
     )
   }
 
-  function getTypeName(object) {
+  function getTypeName(object: unknown) {
     if (typeof object === 'object') {
       return object === null ? 'null' : object.constructor.name
     }