Add example extension for chat variables. Allow registering custom text processing functions for extensions

public/scripts/extensions/variables/index.js

@@ -0,0 +1,62 @@
+import { getContext } from "../../extensions.js";
+
+/**
+ * Gets a chat variable from the current chat metadata.
+ * @param {string} name The name of the variable to get.
+ * @returns {string} The value of the variable.
+ */
+function getChatVariable(name) {
+    const metadata = getContext().chatMetadata;
+
+    if (!metadata) {
+        return '';
+    }
+
+    if (!metadata.variables) {
+        metadata.variables = {};
+        return '';
+    }
+
+    return metadata.variables[name] || '';
+}
+
+/**
+ * Sets a chat variable in the current chat metadata.
+ * @param {string} name The name of the variable to set.
+ * @param {any} value The value of the variable to set.
+ */
+function setChatVariable(name, value) {
+    const metadata = getContext().chatMetadata;
+
+    if (!metadata) {
+        return;
+    }
+
+    if (!metadata.variables) {
+        metadata.variables = {};
+    }
+
+    metadata.variables[name] = value;
+}
+
+function listChatVariables() {
+    const metadata = getContext().chatMetadata;
+
+    if (!metadata) {
+        return '';
+    }
+
+    if (!metadata.variables) {
+        metadata.variables = {};
+        return '';
+    }
+
+    return Object.keys(metadata.variables).map(key => `${key}=${metadata.variables[key]}`).join(';');
+}
+
+jQuery(() => {
+    const context = getContext();
+    context.registerHelper('getvar', getChatVariable);
+    context.registerHelper('setvar', setChatVariable);
+    context.registerHelper('listvar', listChatVariables);
+});