feat: control editor focus (#43882)

* refactor: MultifileEditor to functional component.

* fix: make editor acquire focus once on mount

Now the editors can leave the dom (e.g. if a tab is clicked), but an
editor will only call for focus if the MultifileEditor itself remounts

client/src/templates/Challenges/classic/MultifileEditor.js

@@ -1,5 +1,5 @@
 import PropTypes from 'prop-types';
-import React, { Component } from 'react';
+import React, { useRef } from 'react';
 import { connect } from 'react-redux';
 import { ReflexContainer, ReflexElement, ReflexSplitter } from 'react-reflex';
 import { createSelector } from 'reselect';
@@ -73,14 +73,7 @@ const mapDispatchToProps = {
   updateFile
 };
 
-class MultifileEditor extends Component {
-  focusOnHotkeys() {
-    if (this.props.containerRef.current) {
-      this.props.containerRef.current.focus();
-    }
-  }
-
-  render() {
+const MultifileEditor = props => {
   const {
     challengeFiles,
     containerRef,
@@ -92,7 +85,7 @@ class MultifileEditor extends Component {
     title,
     visibleEditors: { indexcss, indexhtml, indexjs, indexjsx },
     usesMultifileEditor
-    } = this.props;
+  } = props;
   const editorTheme = theme === 'night' ? 'vs-dark-custom' : 'vs-custom';
   // TODO: the tabs mess up the rendering (scroll doesn't work properly and
   // the in-editor description)
@@ -126,6 +119,11 @@ class MultifileEditor extends Component {
   // TODO: the tabs mess up the rendering (scroll doesn't work properly and
   // the in-editor description)
   const targetEditor = getTargetEditor(challengeFiles);
+
+  // Only one editor should be focused and that should happen once, after it has
+  // been mounted. This ref allows the editors to co-ordinate, without having to
+  // resort to redux.
+  const canFocusOnMountRef = useRef(true);
   return (
     <ReflexContainer
       orientation='horizontal'
@@ -138,6 +136,7 @@ class MultifileEditor extends Component {
           {indexjsx && (
             <ReflexElement {...reflexProps} {...resizeProps}>
               <Editor
+                canFocusOnMountRef={canFocusOnMountRef}
                 challengeFiles={challengeFiles}
                 containerRef={containerRef}
                 description={targetEditor === 'indexjsx' ? description : null}
@@ -158,11 +157,10 @@ class MultifileEditor extends Component {
           {indexhtml && (
             <ReflexElement {...reflexProps} {...resizeProps}>
               <Editor
+                canFocusOnMountRef={canFocusOnMountRef}
                 challengeFiles={challengeFiles}
                 containerRef={containerRef}
-                  description={
-                    targetEditor === 'indexhtml' ? description : null
-                  }
+                description={targetEditor === 'indexhtml' ? description : null}
                 editorRef={editorRef}
                 fileKey='indexhtml'
                 initialTests={initialTests}
@@ -180,6 +178,7 @@ class MultifileEditor extends Component {
           {indexcss && (
             <ReflexElement {...reflexProps} {...resizeProps}>
               <Editor
+                canFocusOnMountRef={canFocusOnMountRef}
                 challengeFiles={challengeFiles}
                 containerRef={containerRef}
                 description={targetEditor === 'indexcss' ? description : null}
@@ -201,6 +200,7 @@ class MultifileEditor extends Component {
           {indexjs && (
             <ReflexElement {...reflexProps} {...resizeProps}>
               <Editor
+                canFocusOnMountRef={canFocusOnMountRef}
                 challengeFiles={challengeFiles}
                 containerRef={containerRef}
                 description={targetEditor === 'indexjs' ? description : null}
@@ -219,8 +219,7 @@ class MultifileEditor extends Component {
       </ReflexElement>
     </ReflexContainer>
   );
-  }
-}
+};
 
 MultifileEditor.displayName = 'MultifileEditor';
 MultifileEditor.propTypes = propTypes;

client/src/templates/Challenges/classic/editor.tsx

@@ -57,6 +57,7 @@ interface EditorProps {
   executeChallenge: (options?: { showCompletionModal: boolean }) => void;
   ext: ExtTypes;
   fileKey: FileKeyTypes;
+  canFocusOnMountRef: MutableRefObject<boolean>;
   initialEditorContent: string;
   initialExt: string;
   initTests: (tests: Test[]) => void;
@@ -631,12 +632,15 @@ const Editor = (props: EditorProps): JSX.Element => {
 
   function focusIfTargetEditor() {
     const { editor } = dataRef.current;
-    if (!editor) return;
+    const { canFocusOnMountRef } = props;
+    if (!editor || !canFocusOnMountRef.current) return;
     if (!props.usesMultifileEditor) {
       // Only one editor? Focus it.
       editor.focus();
+      canFocusOnMountRef.current = false;
     } else if (hasEditableRegion()) {
       editor.focus();
+      canFocusOnMountRef.current = false;
     }
   }