Add local storage extension

local-storage.js

@@ -0,0 +1,69 @@
+(function (Scratch) {
+  'use strict';
+  if (!Scratch.extensions.unsandboxed) {
+    throw new Error('Local Storage must be run unsandboxed');
+  }
+
+  const PREFIX = 'untrusted_local_storage_extension:';
+
+  class LocalStorageExt {
+    getInfo() {
+      return {
+        id: 'localstorage',
+        name: 'Local Storage',
+        blocks: [
+          {
+            opcode: 'load',
+            blockType: Scratch.BlockType.REPORTER,
+            text: 'get key [key]',
+            arguments: {
+              key: {
+                type: Scratch.ArgumentType.STRING,
+                defaultValue: 'example',
+              },
+            },
+          },
+          {
+            opcode: 'set',
+            blockType: Scratch.BlockType.COMMAND,
+            text: 'set key [key] to [value]',
+            arguments: {
+              key: {
+                type: Scratch.ArgumentType.STRING,
+                defaultValue: 'example',
+              },
+              value: {
+                type: Scratch.ArgumentType.STRING,
+                defaultValue: '1234',
+              },
+            },
+          },
+        ],
+      };
+    }
+    set(args) {
+      localStorage.setItem(PREFIX + args.key.toString(), JSON.stringify(args.value));
+    }
+    load(args) {
+      try {
+        const storedValue = localStorage.getItem(PREFIX + args.key.toString());
+        if (storedValue !== null) {
+          try {
+            const parsed = JSON.parse(storedValue);
+            if (typeof parsed === 'string' || typeof parsed === 'boolean' || typeof parsed === 'number') {
+              return parsed;
+            }
+          } catch (e) {
+            // JSON.parse failed, ignore
+          }
+          // Return the raw value as a string.
+          return storedValue;
+        }
+      } catch (e) {
+        // localStorage.getItem failed, ignore
+      }
+      return '';
+    }
+  }
+  Scratch.extensions.register(new LocalStorageExt());
+})(Scratch);