js-api: Migrate and test send-message example.

templates/zerver/api/send-message.md

@@ -12,41 +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.
+{generate_code_example(javascript)|/messages:post|example}
-const config = {
-    zuliprc: 'zuliprc',
-};
-
-// Send a stream message
-zulip(config).then((client) => {
-    // Send a message
-    const params = {
-        to: 'Denmark',
-        type: 'stream',
-        subject: 'Castle',
-        content: 'I come not, friends, to steal away your hearts.'
-    }
-
-    client.messages.send(params).then(console.log);
-});
-
-// Send a private message
-zulip(config).then((client) => {
-    // Send a private message
-    const user_id = 9;
-    const params = {
-        to: [user_id],
-        type: 'private',
-        content: 'With mirth and laughter let old wrinkles come.',
-    }
-
-    client.messages.send(params).then(console.log);
-});
-
-```
 
 {tab|curl}
 

zerver/openapi/javascript_examples.js

@@ -62,6 +62,31 @@ const {main, add_example} = ExamplesHandler();
 
 // Declare all the examples below.
 
+add_example('send_message', '/messages:post', 200, async (client) => {
+    // {code_example|start}
+    // Send a stream message
+    let params = {
+        to: 'Denmark',
+        type: 'stream',
+        topic: 'Castle',
+        content: 'I come not, friends, to steal away your hearts.',
+    };
+    const result_1 = await client.messages.send(params);
+    // {code_example|end}
+
+    // {code_example|start}
+    // Send a private message
+    const user_id = 9;
+    params = {
+        to: [user_id],
+        type: 'private',
+        content: 'With mirth and laughter let old wrinkles come.',
+    };
+    const result_2 = await client.messages.send(params);
+    // {code_example|end}
+    return [result_1, result_2];
+});
+
 add_example('create_user', '/users:post', 200, async (client) => {
     // {code_example|start}
     const params = {