enh: Optimize handler (#18)

Author: devethan

src/NumberPadProvider.tsx

@@ -56,26 +56,29 @@ export const NumberPadProvider = ({
   const handleAppend: NumberPadActionContextType['onAppend'] = (
     stack: string,
   ) => {
-    const prevValue = stacks.join('');
-
-    if (prevValue.length >= maxLength) {
+    if (stacks.length >= maxLength) {
       return;
     }
 
     switch (stack) {
       case '.':
-        if (prevValue === '') {
+        if (stacks.length === 0) {
           setStacks(['0', stack]);
           break;
         }
-        if (prevValue.includes('.')) {
+        if (!stacks.includes('.')) {
+          setStacks([...stacks, stack]);
           break;
         }
+        // Skip this append
+        break;
       case '0':
-        if (prevValue === '') {
+        if (stacks.length === 0) {
           setStacks([stack, '.']);
           break;
         }
+        setStacks([...stacks, stack]);
+        break;
       default:
         setStacks([...stacks, stack]);
         break;
@@ -86,14 +89,13 @@ export const NumberPadProvider = ({
   }, []);
   const handleDelete: NumberPadActionContextType['onDelete'] =
     useCallback(() => {
-      const prevValue = stacks.join('');
-
-      if (prevValue === '0.') {
+      if (stacks.length === 2 && stacks[0] === '0' && stacks[1] === '.') {
         handleClear();
         return;
       }
-
-      setStacks(stacks.slice(0, stacks.length - 1));
+      const newStacks = [...stacks];
+      newStacks.pop();
+      setStacks(newStacks);
     }, [handleClear, stacks]);
   const handleGetValue: NumberPadActionContextType['getValue'] = () => {
     return value;