Add local storage extension

extensions/local-storage.js

@@ -0,0 +1,163 @@
+(function (Scratch) {
+  'use strict';
+
+  if (!Scratch.extensions.unsandboxed) {
+    throw new Error('Local Storage must be run unsandboxed');
+  }
+
+  const PREFIX = 'extensions.turbowarp.org/local-storage:';
+  let namespace = '';
+  const getFullStorageKey = () => `${PREFIX}${namespace}`;
+
+  const readFromStorage = () => {
+    try {
+      // localStorage could throw if unsupported
+      const data = localStorage.getItem(getFullStorageKey());
+      if (data) {
+        // JSON.parse could throw if data is invalid
+        const parsed = JSON.parse(data);
+        if (parsed && parsed.data) {
+          // Remove invalid values from the JSON
+          const processed = {};
+          for (const [key, value] of Object.entries(parsed.data)) {
+            if (typeof value === 'number' || typeof value === 'string' || typeof value === 'boolean') {
+              processed[key] = value;
+            }
+          }
+          return processed;
+        }
+      }
+    } catch (error) {
+      console.error('error reading from local storage', error);
+    }
+    return {};
+  };
+
+  const saveToLocalStorage = (data) => {
+    try {
+      if (Object.keys(data).length > 0) {
+        localStorage.setItem(getFullStorageKey(), JSON.stringify({
+          time: Math.round(Date.now() / 1000),
+          data
+        }));
+      } else {
+        localStorage.removeItem(getFullStorageKey());
+      }
+    } catch (error) {
+      console.error('error saving to locacl storage', error);
+    }
+  };
+
+  window.addEventListener('storage', (event) => {
+    if (event.key === getFullStorageKey() && event.storageArea === localStorage) {
+      Scratch.vm.runtime.startHats('localstorage_whenChanged');
+    }
+  });
+
+  class LocalStorage {
+    getInfo() {
+      return {
+        id: 'localstorage',
+        name: 'Local Storage',
+        blocks: [
+          {
+            opcode: 'setProjectId',
+            blockType: Scratch.BlockType.COMMAND,
+            text: 'set storage namespace ID to [ID]',
+            arguments: {
+              ID: {
+                type: Scratch.ArgumentType.STRING,
+                defaultValue: 'project title'
+              }
+            }
+          },
+          {
+            opcode: 'get',
+            blockType: Scratch.BlockType.REPORTER,
+            text: 'get key [KEY]',
+            arguments: {
+              KEY: {
+                type: Scratch.ArgumentType.STRING,
+                defaultValue: 'score',
+              },
+            },
+          },
+          {
+            opcode: 'set',
+            blockType: Scratch.BlockType.COMMAND,
+            text: 'set key [KEY] to [VALUE]',
+            arguments: {
+              KEY: {
+                type: Scratch.ArgumentType.STRING,
+                defaultValue: 'score',
+              },
+              VALUE: {
+                type: Scratch.ArgumentType.STRING,
+                defaultValue: '1000',
+              },
+            },
+          },
+          {
+            opcode: 'remove',
+            blockType: Scratch.BlockType.COMMAND,
+            text: 'delete key [KEY]',
+            arguments: {
+              KEY: {
+                type: Scratch.ArgumentType.STRING,
+                defaultValue: 'score'
+              },
+            },
+          },
+          {
+            opcode: 'removeAll',
+            blockType: Scratch.BlockType.COMMAND,
+            text: 'delete all keys'
+          },
+          {
+            opcode: 'whenChanged',
+            blockType: Scratch.BlockType.HAT,
+            text: 'when another window changes storage',
+            isEdgeActivated: false
+          }
+        ],
+      };
+    }
+    setProjectId({ ID }) {
+      namespace = Scratch.Cast.toString(ID);
+    }
+    get({ KEY }) {
+      if (!namespace) {
+        return 'must use "set storage namespace ID to ..." block first';
+      }
+      const storage = readFromStorage();
+      KEY = Scratch.Cast.toString(KEY);
+      if (Object.prototype.hasOwnProperty.call(storage, KEY)) {
+        return storage[KEY];
+      }
+      return 'key does not exist';
+    }
+    set({ KEY, VALUE }) {
+      if (!namespace) {
+        return;
+      }
+      const storage = readFromStorage();
+      storage[Scratch.Cast.toString(KEY)] = VALUE;
+      saveToLocalStorage(storage);
+    }
+    remove({ KEY }) {
+      if (!namespace) {
+        return;
+      }
+      const storage = readFromStorage();
+      delete storage[Scratch.Cast.toString(KEY)];
+      saveToLocalStorage(storage);
+    }
+    removeAll() {
+      if (!namespace) {
+        return;
+      }
+      saveToLocalStorage({});
+    }
+  }
+  Scratch.extensions.register(new LocalStorage());
+})(Scratch);

website/index.ejs

@@ -410,6 +410,12 @@
           <p>Manipulate characters and text. Originally created by <a href="https://scratch.mit.edu/users/CST1229/">CST1229</a>.</p>
         </div>
 
+        <div class="extension">
+          <%- banner('local-storage') %>
+          <h3>Local Storage</h3>
+          <p>Store data persistently.</p>
+        </div>
+
         <div class="extension">
           <%- banner('clouddata-ping') %>
           <h3>Ping Cloud Data</h3>