UPDATE: Adds web app (#79)

Things missing:

* Browse mode
* Front end tests
* Storybook

webapp/src/components/util.ts

@@ -0,0 +1,42 @@
+import type { Area, Cell } from "./types";
+
+import { columnNameFromNumber } from "@ironcalc/wasm";
+
+/**
+ *  Returns true if the keypress should start editing
+ */
+export function isEditingKey(key: string): boolean {
+  if (key.length !== 1) {
+    return false;
+  }
+  const code = key.codePointAt(0) ?? 0;
+  if (code > 0 && code < 255) {
+    return true;
+  }
+  return false;
+}
+
+export type NavigationKey =
+  | "ArrowRight"
+  | "ArrowLeft"
+  | "ArrowDown"
+  | "ArrowUp"
+  | "Home"
+  | "End";
+
+export const isNavigationKey = (key: string): key is NavigationKey =>
+  ["ArrowRight", "ArrowLeft", "ArrowDown", "ArrowUp", "Home", "End"].includes(
+    key,
+  );
+
+export const getCellAddress = (selectedArea: Area, selectedCell?: Cell) => {
+  const isSingleCell =
+    selectedArea.rowStart === selectedArea.rowEnd &&
+    selectedArea.columnEnd === selectedArea.columnStart;
+
+  return isSingleCell && selectedCell
+    ? `${columnNameFromNumber(selectedCell.column)}${selectedCell.row}`
+    : `${columnNameFromNumber(selectedArea.columnStart)}${
+        selectedArea.rowStart
+      }:${columnNameFromNumber(selectedArea.columnEnd)}${selectedArea.rowEnd}`;
+};