fix: cleanup event listeners on unmount (#301)

src/GraphArea.jsx

@@ -56,11 +56,12 @@ function Graph({
     }, [active, instance, graphID, dispatcher]);
 
     useEffect(() => {
-        if (ref.current) {
-            setContainerDim(ref.current);
-            window.addEventListener('resize', () => setContainerDim(ref.current));
-            setInstance(initialiseNewGraph());
-        }
+        if (!ref.current) return;
+        setContainerDim(ref.current);
+        const handleResize = () => setContainerDim(ref.current);
+        window.addEventListener('resize', handleResize);
+        setInstance(initialiseNewGraph());
+        return () => window.removeEventListener('resize', handleResize);
     }, [ref]);
 
     // Update theme when darkMode changes

src/component/File-drag-drop.jsx

@@ -6,42 +6,58 @@ import { readFile } from '../toolbarActions/toolbarFunctions';
 
 const app = ({ superState, dispatcher }) => {
     const fileRef = React.useRef();
+    const superStateRef = React.useRef(superState);
+    const dispatcherRef = React.useRef(dispatcher);
+
+    useEffect(() => {
+        superStateRef.current = superState;
+        dispatcherRef.current = dispatcher;
+    });
 
     useEffect(() => {
         dispatcher({ type: T.SET_FILE_REF, payload: fileRef });
         const p = document.getElementsByTagName('body')[0];
         const c = document.getElementsByClassName('drag-drop-area')[0];
         let cc = 0;
-        p.addEventListener('dragenter', (e) => {
+
+        const onDragEnter = (e) => {
             e.preventDefault();
             cc += 1;
             if (cc === 1) c.classList.remove('hidden');
-        });
-        p.addEventListener('dragleave', (e) => {
+        };
+        const onDragLeave = (e) => {
             e.preventDefault();
             cc -= 1;
             if (cc === 0) c.classList.add('hidden');
-        });
-
-        p.addEventListener('dragover', (e) => {
+        };
+        const onDragOver = (e) => { e.preventDefault(); };
+        const onDragReset = (e) => {
             e.preventDefault();
-        });
-        ['dragend', 'dragexit', 'drop'].forEach((dragEvent) => {
-            p.addEventListener(dragEvent, (e) => {
-                e.preventDefault();
-                cc = 0;
-                c.classList.add('hidden');
-            });
-        });
-
-        p.addEventListener('drop', (e) => {
+            cc = 0;
+            c.classList.add('hidden');
+        };
+        const onDrop = (e) => {
             e.preventDefault();
             fileRef.current.value = null;
             if (e.dataTransfer.files.length === 1
                 && e.dataTransfer.files[0].name.split('.').slice(-1)[0] === 'graphml') {
-                readFile(superState, dispatcher, e.dataTransfer.files[0]);
+                readFile(superStateRef.current, dispatcherRef.current, e.dataTransfer.files[0]);
             }
-        });
+        };
+
+        p.addEventListener('dragenter', onDragEnter);
+        p.addEventListener('dragleave', onDragLeave);
+        p.addEventListener('dragover', onDragOver);
+        ['dragend', 'dragexit', 'drop'].forEach((dragEvent) => p.addEventListener(dragEvent, onDragReset));
+        p.addEventListener('drop', onDrop);
+
+        return () => {
+            p.removeEventListener('dragenter', onDragEnter);
+            p.removeEventListener('dragleave', onDragLeave);
+            p.removeEventListener('dragover', onDragOver);
+            ['dragend', 'dragexit', 'drop'].forEach((dragEvent) => p.removeEventListener(dragEvent, onDragReset));
+            p.removeEventListener('drop', onDrop);
+        };
     }, []);
     return (
         <div className="drag-drop-area hidden">

src/component/Header.jsx

@@ -31,12 +31,14 @@ const setHotKeys = (actions) => {
         event.preventDefault();
         map[handler.shortcut].click();
     });
+    return keys;
 };
 
 const Header = ({ superState, dispatcher }) => {
     const actions = toolbarList(superState, dispatcher);
     React.useEffect(() => {
-        setHotKeys(actions, superState, dispatcher);
+        const keys = setHotKeys(actions);
+        return () => { if (keys) hotkeys.unbind(keys); };
     }, []);
 
     return (

src/component/TabBar.jsx

@@ -63,6 +63,11 @@ const TabBar = ({ superState, dispatcher }) => {
             const el = document.querySelector('.tab.tab-graph.selected > .tab-act.close');
             if (el) el.click();
         });
+        return () => {
+            hotkeys.unbind('ctrl+shift+m,command+shift+m');
+            hotkeys.unbind('ctrl+shift+e,command+shift+e');
+            hotkeys.unbind('ctrl+shift+l,command+shift+l');
+        };
     }, []);
 
     return (