feat: add keyboard shortcuts for delete, escape, and swap

samples/dev/index.html

@@ -213,7 +213,7 @@
       <input id="input" class="hidden-input" type="text" autocomplete="off" aria-hidden="true" tabindex="-1">
 
       <div class="input-row">
-        <div class="hint">Keyboard works globally: digits, numpad, Enter, Backspace, +, -, *, /, %, ^</div>
+        <div class="hint">Keyboard works globally: digits, numpad, Enter, Backspace, Delete, →, +, -, *, /, %, ^</div>
         <select id="angleMode">
           <option value="deg">Degrees</option>
           <option value="rad">Radians</option>
@@ -402,8 +402,10 @@
 
       const keyMap = {
         Enter: { type: 'command', value: 'enter' },
-        Backspace: { type: 'edit', value: 'Backspace' },
+        Backspace: { type: 'stackOrEdit', value: 'drop' },
-        Escape: { type: 'command', value: 'clear' },
+        Delete: { type: 'command', value: 'clear' },
+        Escape: { type: 'cancelEdit' },
+        ArrowRight: { type: 'command', value: 'swap' },
         '+': { type: 'command', value: 'add' },
         '-': { type: 'command', value: 'sub' },
         '*': { type: 'command', value: 'mul' },
@@ -451,6 +453,18 @@
       }
 
       try {
+        if (action.type === 'cancelEdit') {
+          if (!calc.isEditing) {
+            return;
+          }
+          event.preventDefault();
+          calc.inputValue = '';
+          calc.isEditing = false;
+          syncInputFromState();
+          render();
+          return;
+        }
+
         event.preventDefault();
 
         if (action.type === 'input') {
@@ -459,10 +473,12 @@
           return;
         }
 
-        if (action.type === 'edit') {
+        if (action.type === 'stackOrEdit') {
           if (calc.isEditing) {
-            editXWithKey(action.value);
+            editXWithKey('Backspace');
             render();
+          } else {
+            execute(action.value);
           }
           return;
         }