TaskList: convert to a pure functional component.

src/components/TaskList.tsx

@@ -26,14 +26,13 @@ const sortSelector = createSelector(
   (entries) => entries.sort((a, b) => a.title.localeCompare(b.title))
 );
 
-class TaskList extends React.PureComponent {
-  public props: {
+interface PropsType {
   entries: TaskType[];
   onItemClick: (entry: TaskType) => void;
-  };
+}
 
-  public render() {
-    const entries = this.props.entries.filter((x) => !x.finished);
+export default React.memo(function TaskList(props: PropsType) {
+  const entries = props.entries.filter((x) => !x.finished);
   const sortedEntries = sortSelector(entries);
 
   const itemList = sortedEntries.map((entry) => {
@@ -43,7 +42,7 @@ class TaskList extends React.PureComponent {
       <TaskListItem
         key={uid}
         entry={entry}
-          onClick={this.props.onItemClick}
+        onClick={props.onItemClick}
       />
     );
   });
@@ -53,7 +52,4 @@ class TaskList extends React.PureComponent {
       {itemList}
     </List>
   );
-  }
-}
-
-export default TaskList;
+});