fix lint errors in initializeSwipeGestures (#8972)

Co-authored-by: Nick Taylor <nick@iamdeveloper.com

app/assets/javascripts/initializers/initializeSwipeGestures.js

@@ -1,61 +1,112 @@
-function initializeSwipeGestures(){
-  initializeSwipeGestures.called = true;
-  swipeState = "middle";
-  setTimeout(function(){
+/* global slideSidebar, swipeState: true */
+'use strict';
 
-    // window.onload=function(){
-    (function(d){
-    var
-    ce=function(e,n){var a=document.createEvent("CustomEvent");a.initCustomEvent(n,true,true,e.target);e.target.dispatchEvent(a);a=null;return false},
-    nm=true,sp={x:0,y:0},ep={x:0,y:0},
-    touch={
-      touchstart:function(e){sp={x:e.touches[0].pageX,y:e.touches[0].pageY,scrollY:window.scrollY}},
-      touchmove:function(e){nm=false;ep={x:e.touches[0].pageX,y:e.touches[0].pageY,scrollY:window.scrollY}},
-      touchend:function(e){
-        if(nm){ce(e,'fc')}
-        else {
-          var x=ep.x-sp.x,xr=Math.abs(x),y=ep.y-sp.y,yr=Math.abs(y),absScroll=Math.abs(sp.scrollY-ep.scrollY);
-          if(Math.max(xr,yr)>15){
-            var shouldScroll = (xr/2)>yr && absScroll < 5;
-            ce(e,(shouldScroll?(x<0?'swl':'swr'):(y<0?'swu':'swd')))
-          }
+function slideContent(d) {
+  var ce = function (e, n) {
+      var a = document.createEvent('CustomEvent');
+      a.initCustomEvent(n, true, true, e.target);
+      e.target.dispatchEvent(a);
+      a = null;
+      return false;
+    },
+    nm = true,
+    sp = { x: 0, y: 0 },
+    ep = { x: 0, y: 0 },
+    touch = {
+      touchstart: function (e) {
+        sp = {
+          x: e.touches[0].pageX,
+          y: e.touches[0].pageY,
+          scrollY: window.scrollY,
         };
-        nm=true
       },
-      touchcancel:function(e){nm=false}
+      touchmove: function (e) {
+        nm = false;
+        ep = {
+          x: e.touches[0].pageX,
+          y: e.touches[0].pageY,
+          scrollY: window.scrollY,
+        };
+      },
+      touchend: function (e) {
+        if (nm) {
+          ce(e, 'fc');
+        } else {
+          var x = ep.x - sp.x,
+            xr = Math.abs(x),
+            y = ep.y - sp.y,
+            yr = Math.abs(y),
+            absScroll = Math.abs(sp.scrollY - ep.scrollY);
+          if (Math.max(xr, yr) > 15) {
+            var shouldScroll = xr / 2 > yr && absScroll < 5;
+            ce(
+              e,
+              shouldScroll ? (x < 0 ? 'swl' : 'swr') : y < 0 ? 'swu' : 'swd',
+            );
+          }
+        }
+        nm = true;
+      },
+      touchcancel: function (e) {
+        nm = false;
+      },
     };
-    for(var a in touch){d.addEventListener(a,touch[a],false);}
-    })(document);
-    var h=function(e){console.log(e.type,e)};
-    document.body.addEventListener('swl',handleSwipeLeft,false);
-    document.body.addEventListener('swr',handleSwipeRight,false);
-  },50)
+  for (var a in touch) {
+    d.addEventListener(a, touch[a], false);
+  }
 }
 
+function initializeSwipeGestures() {
+  initializeSwipeGestures.called = true;
+  let swipeState = 'middle';
+  setTimeout(function () {
+    // window.onload=function(){
+    slideContent(document);
+    var h = function (e) {
+      console.log(e.type, e);
+    };
+    document.body.addEventListener(
+      'swl',
+      (e) => {
+        swipeState = handleSwipeLeft(e, swipeState);
+      },
+      false,
+    );
+    document.body.addEventListener(
+      'swr',
+      (e) => {
+        swipeState = handleSwipeRight(e, swipeState);
+      },
+      false,
+    );
+  }, 50);
+}
 
-function handleSwipeLeft(e){
-  if (!document.getElementById("on-page-nav-controls")){
+function handleSwipeLeft(e, swipeState) {
+  if (!document.getElementById('on-page-nav-controls')) {
     return;
   }
-  if (swipeState == "middle"){
-    swipeState = "right"
-    slideSidebar("right","intoView");
-  }
-  else{
-    swipeState = "middle"
-    slideSidebar("left","outOfView");
+  if (swipeState == 'middle') {
+    swipeState = 'right';
+    slideSidebar('right', 'intoView');
+    return swipeState;
+  } else {
+    swipeState = 'middle';
+    slideSidebar('left', 'outOfView');
+    return swipeState;
   }
 }
-function handleSwipeRight(e){
-  if (!document.getElementById("on-page-nav-controls")){
+function handleSwipeRight(e, swipeState) {
+  if (!document.getElementById('on-page-nav-controls')) {
     return;
   }
-  if (swipeState == "middle"){
-    swipeState = "left"
-    slideSidebar("left","intoView");
-  }
-  else{
-    swipeState = "middle"
-    slideSidebar("right","outOfView");
+  if (swipeState == 'middle') {
+    swipeState = 'left';
+    slideSidebar('left', 'intoView');
+    return swipeState;
+  } else {
+    swipeState = 'middle';
+    slideSidebar('right', 'outOfView');
+    return swipeState;
   }
 }