Fixes eslint issues in back-to-top.js (#685)

* fixes eslint issues in back-to-top.js

* fix: change quotes to single

---------

Co-authored-by: Lee Mills <lee@leemills.dev>

js/back-to-top.js

@@ -2,7 +2,7 @@
  * @file Drupal behavior for 'back to top' link.
  */
 
-(function (Drupal) {
+(function localgovBackToTopScript(Drupal) {
   Drupal.behaviors.localgovBackToTop = {
     attach(context) {
       /**
@@ -19,28 +19,29 @@
        *   past the top of the viewport. In practices, there's only one of
        *   these since we've only targeted one element.
        */
+      const [backToTop] = once('back-to-top', '.back-to-top', context);
+      const [backToTopTarget] = once(
+        'back-to-top-target',
+        '.back-to-top-target',
+        context,
+      );
+
       function observerCallback(entries) {
         entries.forEach((entry) => {
-          backToTop.hidden = (
+          backToTop.hidden =
             entry.isIntersecting ||
             (!entry.isIntersecting && entry.boundingClientRect.top <= 0)
-          ) ? false : 'until-hidden';
+              ? false
+              : 'until-hidden';
         });
       }
 
-      const [backToTop] = once('back-to-top', '.back-to-top', context);
-      const [backToTopTarget] = once(
-        'back-to-top-target',
-        '.back-to-top-target',
-        context,
-      );
       const minContentViewportRatio = parseFloat(
         backToTop?.dataset?.minContentViewportRatio ?? 1.5,
         10,
       );
       const viewportHeight = window.innerHeight;
       const documentHeight = document.documentElement.offsetHeight;
-      let intersectionObserver;
 
       if (
         !backToTop ||
@@ -53,10 +54,12 @@
       // Create an element absolutely positioned at our threshold.
       backToTopTarget.style.position = 'absolute';
       backToTopTarget.style.top = `${viewportHeight * minContentViewportRatio}px`;
-      backToTop.addEventListener('click', (event) => event.target.hidden = 'until-found');
+      backToTop.addEventListener('click', (event) => {
+        event.target.hidden = 'until-found';
+      });
 
       // Create an IntersectionObserver.
-      intersectionObserver = new IntersectionObserver(observerCallback, {
+      const intersectionObserver = new IntersectionObserver(observerCallback, {
         rootMargin: '16px',
       });
       intersectionObserver.observe(backToTopTarget);