allowTouchMove receive touch event

README.md

@@ -288,13 +288,19 @@ To disable scrolling on iOS, `disableBodyScroll` prevents `touchmove` events.
 However, there are cases where you have called `disableBodyScroll` on an
 element, but its children still require `touchmove` events to function.
 
+The `allowTouchMove` option should be a function which returns a boolean. It is
+passed two arguments: the element receiving the touch event, and the touch event
+itself. If a truthy value is returned, the touch event will not be prevented.
+
 See below for 2 use cases:
 
 ##### Simple
 
 ```javascript
 disableBodyScroll(container, {
-  allowTouchMove: el => el.tagName === 'TEXTAREA',
+  allowTouchMove(el) {
+    return el.tagName === 'TEXTAREA';
+  },
 });
 ```
 
@@ -304,12 +310,11 @@ Javascript:
 
 ```javascript
 disableBodyScroll(container, {
-  allowTouchMove: el => {
+  allowTouchMove(el, event) {
     while (el && el !== document.body) {
       if (el.getAttribute('body-scroll-lock-ignore') !== null) {
         return true;
       }
-
       el = el.parentElement;
     }
   },

src/bodyScrollLock.js

@@ -2,9 +2,11 @@
 // Adopted and modified solution from Bohdan Didukh (2017)
 // https://stackoverflow.com/questions/41594997/ios-10-safari-prevent-scrolling-behind-a-fixed-overlay-and-maintain-scroll-posi
 
+type HandleScrollEvent = TouchEvent;
+
 export interface BodyScrollOptions {
   reserveScrollBarGap?: boolean;
-  allowTouchMove?: (el: any) => boolean;
+  allowTouchMove?: (el: any, event: HandleScrollEvent) => boolean;
 }
 
 interface Lock {
@@ -31,7 +33,6 @@ const isIosDevice =
   window.navigator.platform &&
   (/iP(ad|hone|od)/.test(window.navigator.platform) ||
     (window.navigator.platform === 'MacIntel' && window.navigator.maxTouchPoints > 1));
-type HandleScrollEvent = TouchEvent;
 
 let locks: Array<Lock> = [];
 let documentListenerAdded: boolean = false;
@@ -41,9 +42,9 @@ let previousBodyPosition;
 let previousBodyPaddingRight;
 
 // returns true if `el` should be allowed to receive touchmove events.
-const allowTouchMove = (el: EventTarget): boolean =>
+const allowTouchMove = (el: EventTarget, event: HandleScrollEvent): boolean =>
   locks.some(lock => {
-    if (lock.options.allowTouchMove && lock.options.allowTouchMove(el)) {
+    if (lock.options.allowTouchMove && lock.options.allowTouchMove(el, event)) {
       return true;
     }
 
@@ -57,7 +58,7 @@ const preventDefault = (rawEvent: HandleScrollEvent): boolean => {
   // Recall that we do document.addEventListener('touchmove', preventDefault, { passive: false })
   // in disableBodyScroll - so if we provide this opportunity to allowTouchMove, then
   // the touchmove event on document will break.
-  if (allowTouchMove(e.target)) {
+  if (allowTouchMove(e.target, e)) {
     return true;
   }
 
@@ -158,7 +159,7 @@ const isTargetElementTotallyScrolled = (targetElement: any): boolean =>
 const handleScroll = (event: HandleScrollEvent, targetElement: any): boolean => {
   const clientY = event.targetTouches[0].clientY - initialClientY;
 
-  if (allowTouchMove(event.target)) {
+  if (allowTouchMove(event.target, event)) {
     return false;
   }