[null] Small steps

Author: jamesgpearce

src/common/other.ts

@@ -37,6 +37,8 @@ export const isInstanceOf = (
 export const isUndefined = (thing: unknown): thing is undefined | null =>
   thing == undefined;
 
+export const isNull = (thing: unknown): thing is null => thing == null;
+
 export const ifNotUndefined = <Value, Return>(
   value: Value | null | undefined,
   then: (value: Value) => Return,

src/persisters/common/database/sqlite.ts

@@ -9,7 +9,12 @@ import type {
 } from '../../../@types/persisters/index.d.ts';
 import {collValues} from '../../../common/coll.ts';
 import {IdObj} from '../../../common/obj.ts';
-import {startInterval, stopInterval, tryCatch} from '../../../common/other.ts';
+import {
+  isNull,
+  startInterval,
+  stopInterval,
+  tryCatch,
+} from '../../../common/other.ts';
 import {EMPTY_STRING} from '../../../common/strings.ts';
 import {
   DATA_VERSION,
@@ -59,7 +64,7 @@ export const createCustomSqlitePersister = <
   const addPersisterListener = (
     listener: PersisterListener<Persist>,
   ): (() => void) => {
-    let interval: NodeJS.Timeout;
+    let interval: number;
 
     const startPolling = () =>
       (interval = startInterval(
@@ -71,7 +76,7 @@ export const createCustomSqlitePersister = <
                 ` ${DATA_VERSION} d,${SCHEMA_VERSION} s,TOTAL_CHANGES() c FROM ${PRAGMA}${DATA_VERSION} JOIN ${PRAGMA}${SCHEMA_VERSION}`,
             )) as [IdObj<number>];
             if (d != dataVersion || s != schemaVersion || c != totalChanges) {
-              if (dataVersion != null) {
+              if (!isNull(dataVersion)) {
                 listener();
               }
               dataVersion = d;

src/ui-react-inspector/actions/common.tsx

@@ -8,6 +8,10 @@ import type {
   ValuesProps,
 } from '../../@types/ui-react/index.d.ts';
 import {useCallback, useEffect, useState} from '../../common/react.ts';
+import {  isUndefined 
+
+  
+} from '../../common/other.ts';
 
 export type OnDoneProp = {readonly onDone: () => void};
 
@@ -31,6 +35,8 @@ export const getNewIdFromSuggestedId = (
 
 export const ConfirmableActions = <
   Props extends TableProps | RowProps | CellProps | ValuesProps | ValueProps,
+
+  
 >({
   actions,
   ...props
@@ -41,13 +47,13 @@ export const ConfirmableActions = <
     component: ComponentType<OnDoneProp & Props>,
   ][];
 } & Props) => {
-  const [confirming, setConfirming] = useState<number | null>();
-  const handleDone = useCallback(() => setConfirming(null), []);
+  const [confirming, setConfirming] = useState<number | undefined>();
+  const handleDone = useCallback(() => setConfirming(undefined), []);
 
   useEffect(() => {
-    if (confirming != null) {
+    if (!isUndefined(confirming)) {
       const handleKeyDown = (e: KeyboardEvent) => {
-        if (confirming != null && e.key === 'Escape') {
+        if (!isUndefined(confirming) && e.key === 'Escape') {
           e.preventDefault();
           handleDone();
         }
@@ -57,7 +63,7 @@ export const ConfirmableActions = <
     }
   }, [confirming, handleDone]);
 
-  if (confirming != null) {
+  if (!isUndefined(confirming)) {
     const [, , Component] = actions[confirming];
     return (
       <>