Util getScrollParent() -> getScrollElement()

* doc and rename to match actual functionality

Author: adumesny

doc/CHANGES.md

@@ -5,6 +5,7 @@ Change log
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 **Table of Contents**  *generated with [DocToc](http://doctoc.herokuapp.com/)*
 
+- [4.2.2-dev](#422-dev)
 - [4.2.2 (2021-4-23)](#422-2021-4-23)
 - [4.2.1 (2021-4-18)](#421-2021-4-18)
 - [4.2.0 (2021-4-11)](#420-2021-4-11)
@@ -55,6 +56,11 @@ Change log
 - [v0.1.0 (2014-11-18)](#v010-2014-11-18)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
+## 4.2.2-dev
+
+- `Utils.getScrollParent()` -> `getScrollElement()` rename
+- fix [#1745](https://github.com/gridstack/gridstack.js/issues/1745) digression on scrolling in v4.2.1. Thanks [@Manfred-on-github](https://github.com/Manfred-on-github) for fixing your prev change.
+
 ## 4.2.2 (2021-4-23)
 
 - fix [#1684](https://github.com/gridstack/gridstack.js/issues/1684) [#1550](https://github.com/gridstack/gridstack.js/issues/1550) mac Safari H5 draggable broken in 4.0.1. Thanks [@wurambo](https://github.com/wurambo)

spec/utils-spec.ts

@@ -123,7 +123,7 @@ describe('gridstack utils', function() {
       expect(el.style.position).toEqual('');
 
       // bogus test
-      expect(Utils.getScrollParent(el)).not.toBe(null);
+      expect(Utils.getScrollElement(el)).not.toBe(null);
       // bogus test
       Utils.updateScrollPosition(el, {top: 20}, 10);
     });

src/h5/dd-resizable.ts

@@ -154,7 +154,7 @@ export class DDResizable extends DDBaseImplement implements HTMLElementExtendOpt
   /** @internal */
   private _resizeStart(event: MouseEvent): DDResizable {
     this.originalRect = this.el.getBoundingClientRect();
-    this.scrollEl = Utils.getScrollParent(this.el);
+    this.scrollEl = Utils.getScrollElement(this.el);
     this.scrollY = this.scrollEl.scrollTop;
     this.startEvent = event;
     this._setupHelper();

src/utils.ts

@@ -291,16 +291,16 @@ export class Utils {
     }
   }
 
-  /** @internal */
-  static getScrollParent(el: HTMLElement): HTMLElement {
-    if (el === null) return document.scrollingElement as HTMLElement;
+  /** @internal returns the passed element if scrollable, else the closest parent that will, up to the entire document scrolling element */
+  static getScrollElement(el?: HTMLElement): HTMLElement {
+    if (!el) return document.scrollingElement as HTMLElement;
     const style = getComputedStyle(el);
     const overflowRegex = /(auto|scroll)/;
 
     if (overflowRegex.test(style.overflow + style.overflowY)) {
       return el;
     } else {
-      return this.getScrollParent(el.parentElement);
+      return this.getScrollElement(el.parentElement);
     }
   }
 
@@ -317,7 +317,7 @@ export class Utils {
       // to get entire widget on screen
       let offsetDiffDown = rect.bottom - innerHeightOrClientHeight;
       let offsetDiffUp = rect.top;
-      let scrollEl = this.getScrollParent(el);
+      let scrollEl = this.getScrollElement(el);
       if (scrollEl !== null) {
         let prevScroll = scrollEl.scrollTop;
         if (rect.top < 0 && distance < 0) {
@@ -349,7 +349,7 @@ export class Utils {
    * @param distance Distance from the V edges to start scrolling
    */
   static updateScrollResize(event: MouseEvent, el: HTMLElement, distance: number): void {
-    const scrollEl = this.getScrollParent(el);
+    const scrollEl = this.getScrollElement(el);
     const height = scrollEl.clientHeight;
     const offsetTop = scrollEl.getBoundingClientRect().top;
     const pointerPosY = event.clientY - offsetTop;