js_examples: Migrate and test render_message example.

templates/zerver/api/render-message.md

@@ -12,23 +12,8 @@
 {tab|js}
 
 More examples and documentation can be found [here](https://github.com/zulip/zulip-js).
-```js
-const zulip = require('zulip-js');
 
-// Pass the path to your zuliprc file here.
-const config = {
-    zuliprc: 'zuliprc',
-};
-
-zulip(config).then((client) => {
-    // Render a message
-    const params = {
-        content: '**foo**',
-    };
-
-    client.messages.render(params).then(console.log);
-});
-```
+{generate_code_example(javascript)|/messages/render:post|example}
 
 {tab|curl}
 

zerver/openapi/javascript_examples.js

@@ -46,6 +46,7 @@ const ExamplesHandler = function () {
         await generate_validation_data(client, examples.get_subscriptions);
         await generate_validation_data(client, examples.get_users);
         await generate_validation_data(client, examples.register_queue);
+        await generate_validation_data(client, examples.render_message);
 
         console.log(JSON.stringify(response_data));
         return;
@@ -200,4 +201,15 @@ add_example('register_queue', '/register:post', 200, async (client) => {
     // {code_example|end}
 });
 
+add_example('render_message', '/messages/render:post', 200, async (client) => {
+    // {code_example|start}
+    // Render a message
+    const params = {
+        content: '**foo**',
+    };
+
+    return await client.messages.render(params);
+    // {code_example|end}
+});
+
 main();