fix(pasting): preserve scroll position

Author: peyerluk

src/cursor.js

@@ -1,5 +1,6 @@
 import $ from 'jquery'
 import rangy from 'rangy'
+import viewport from './util/viewport'
 
 import * as content from './content'
 import * as parser from './parser'
@@ -92,7 +93,9 @@ export default class Cursor {
     // Without setting focus() Firefox is not happy (seems setting a selection is not enough.
     // Probably because Firefox can handle multiple selections).
     if (this.win.document.activeElement !== this.host) {
+      const {x, y} = viewport.getScrollPosition(this.win)
       $(this.host).focus()
+      this.win.scrollTo(x, y)
     }
     rangy.getSelection(this.win).setSingleRange(this.range)
   }
@@ -140,12 +143,9 @@ export default class Cursor {
     const coords = this.range.nativeRange.getBoundingClientRect()
     if (positioning === 'fixed') return coords
 
-    // code from mdn: https://developer.mozilla.org/en-US/docs/Web/API/window.scrollX
-    const win = this.win
-    const x = (win.pageXOffset !== undefined) ? win.pageXOffset : (win.document.documentElement || win.document.body.parentNode || win.document.body).scrollLeft
-    const y = (win.pageYOffset !== undefined) ? win.pageYOffset : (win.document.documentElement || win.document.body.parentNode || win.document.body).scrollTop
 
     // translate into absolute positions
+    const {x, y} = viewport.getScrollPosition(this.win)
     return {
       top: coords.top + y,
       bottom: coords.bottom + y,

src/util/viewport.js

@@ -0,0 +1,6 @@
+// code from mdn: https://developer.mozilla.org/en-US/docs/Web/API/window.scrollX
+export function getScrollPosition (win) {
+  const x = (win.pageXOffset !== undefined) ? win.pageXOffset : (win.document.documentElement || win.document.body.parentNode || win.document.body).scrollLeft
+  const y = (win.pageYOffset !== undefined) ? win.pageYOffset : (win.document.documentElement || win.document.body.parentNode || win.document.body).scrollTop
+  return {x, y}
+}