feat: respond with action and generated locator (#181)

Closes https://github.com/microsoft/playwright-mcp/issues/163

src/javascript.ts

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// adapted from:
+// - https://github.com/microsoft/playwright/blob/76ee48dc9d4034536e3ec5b2c7ce8be3b79418a8/packages/playwright-core/src/utils/isomorphic/stringUtils.ts
+// - https://github.com/microsoft/playwright/blob/76ee48dc9d4034536e3ec5b2c7ce8be3b79418a8/packages/playwright-core/src/server/codegen/javascript.ts
+
+// NOTE: this function should not be used to escape any selectors.
+export function escapeWithQuotes(text: string, char: string = '\'') {
+  const stringified = JSON.stringify(text);
+  const escapedText = stringified.substring(1, stringified.length - 1).replace(/\\"/g, '"');
+  if (char === '\'')
+    return char + escapedText.replace(/[']/g, '\\\'') + char;
+  if (char === '"')
+    return char + escapedText.replace(/["]/g, '\\"') + char;
+  if (char === '`')
+    return char + escapedText.replace(/[`]/g, '`') + char;
+  throw new Error('Invalid escape char');
+}
+
+export function quote(text: string) {
+  return escapeWithQuotes(text, '\'');
+}
+
+export function formatObject(value: any, indent = '  '): string {
+  if (typeof value === 'string')
+    return quote(value);
+  if (Array.isArray(value))
+    return `[${value.map(o => formatObject(o)).join(', ')}]`;
+  if (typeof value === 'object') {
+    const keys = Object.keys(value).filter(key => value[key] !== undefined).sort();
+    if (!keys.length)
+      return '{}';
+    const tokens: string[] = [];
+    for (const key of keys)
+      tokens.push(`${key}: ${formatObject(value[key])}`);
+    return `{\n${indent}${tokens.join(`,\n${indent}`)}\n}`;
+  }
+  return String(value);
+}