Add fallback copy handler.

CHANGELOG.md

@@ -6,6 +6,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 - [#713](https://github.com/plotly/dash-table/pull/713) Update from React 16.8.6 to 16.13.0
 
+### Fixed
+- [#725](https://github.com/plotly/dash-table/pull/725) Fix bug in which copy events were not triggered except upon selection of a different cell.
+
 ## [4.6.1] - 2020-02-27
 ### Added
 - [#711](https://github.com/plotly/dash-table/pull/711) Added R examples to package help

src/dash-table/components/ControlledTable/index.tsx

@@ -115,11 +115,12 @@ export default class ControlledTable extends PureComponent<ControlledTableProps>
     }
 
     componentDidMount() {
-        // Fallback method for paste handling in Chrome
+        // Fallback method for copy/paste handling in Chrome
         // when no input element has focused inside the table
         window.addEventListener('resize', this.forceHandleResize);
         document.addEventListener('mousedown', this.handleClick);
         document.addEventListener('paste', this.handlePaste);
+        document.addEventListener('copy', this.handleCopy);
 
         const {
             active_cell,
@@ -222,6 +223,16 @@ export default class ControlledTable extends PureComponent<ControlledTableProps>
         }
     }
 
+    handleCopy = (event: any) => {
+        // no need to check for target as this will only be called if
+        // a child fails to handle the copy event (e.g table, table input)
+        // make sure the active element is in the scope of the component
+        const $el = this.$el;
+        if ($el && $el.contains(document.activeElement)) {
+            this.onCopy(event);
+        }
+    }
+
     forceHandleResize = () => this.handleResize(true);
 
     handleResize = (force: boolean = false) => {

tests/selenium/test_basic_copy_paste.py

@@ -235,3 +235,25 @@ def test_tbcp008_copy_paste_between_tables_with_hidden_columns(test):
                 target.cell(row + 10, col).get_text()
                 == target.cell(row, col).get_text()
             )
+
+
+def test_tbcp009_copy_paste_to_external_element(test):
+    app = get_app()
+
+    new_layout = html.Div([html.Textarea(id="clipboard-content"), app.layout])
+
+    app.layout = new_layout
+
+    test.start_server(app)
+
+    target = test.table("table")
+    with test.hold(Keys.SHIFT):
+        target.cell(0, 0).click()
+        target.cell(2, 1).click()
+    test.copy()
+
+    target.cell(2, 2).click()
+    test.paste()
+    test.driver.find_element_by_id("clipboard-content").click()
+
+    test.paste()