Adds topk example for RedisBloom (#1837)

* Adds topk example.

* Update topk.js

Co-authored-by: Leibale Eidelman <leibale1998@gmail.com>

examples/README.md

@@ -14,6 +14,7 @@ This folder contains example scripts showing how to use Node Redis in different
 | `set-scan.js`               | An example script that shows how to use the SSCAN iterator functionality                                       |
 | `stream-producer.js`        | Adds entries to a [Redis Stream](https://redis.io/topics/streams-intro) using the `XADD` command               |
 | `stream-consumer.js`        | Reads entries from a [Redis Stream](https://redis.io/topics/streams-intro) using the blocking `XREAD` command  |
+| `topk.js`                   | Use the [RedisBloom](https://redisbloom.io) TopK to track the most frequently seen items.                      |
 
 ## Contributing
 

examples/topk.js

@@ -0,0 +1,94 @@
+// This example demonstrates the use of the Top K 
+// in the RedisBloom module (https://redisbloom.io/)
+
+import { createClient } from 'redis';
+
+async function topK() {
+  const client = createClient();
+
+  await client.connect();
+
+  // Delete any pre-existing Top K.
+  await client.del('mytopk');
+
+  // Reserve a Top K to track the 10 most common items.
+  // https://oss.redis.com/redisbloom/TopK_Commands/#topkreserve
+  try {
+    await client.topK.reserve('mytopk', 10);
+    console.log('Reserved Top K.');
+  } catch (e) {
+    if (e.message.endsWith('key already exists')) {
+      console.log('Top K already reserved.');
+    } else {
+      console.log('Error, maybe RedisBloom is not installed?:');
+      console.log(e);
+    }
+  }
+
+  const teamMembers = [
+    'leibale',
+    'simon',
+    'guy',
+    'suze',
+    'brian',
+    'steve',
+    'kyleb',
+    'kyleo',
+    'josefin',
+    'alex',
+    'nava',
+    'lance',
+    'rachel',
+    'kaitlyn'
+  ];
+
+  // Add random counts for random team members with TOPK.INCRBY
+  for (let n = 0; n < 1000; n++) {
+    const teamMember = teamMembers[Math.floor(Math.random() * teamMembers.length)];
+    const points = Math.floor(Math.random() * 1000) + 1;
+    await client.topK.incrBy('mytopk', {
+      item: teamMember,
+      incrementBy: points
+    });
+    console.log(`Added ${points} points for ${teamMember}.`);
+  }
+
+  // List out the top 10 with TOPK.LIST
+  const top10 = await client.topK.list('mytopk');
+  console.log('The top 10:');
+  // top10 looks like this:
+  //   [
+  //     'guy',     'nava',
+  //     'kaitlyn', 'brian',
+  //     'simon',   'suze',
+  //     'lance',   'alex',
+  //     'steve',   'kyleo'
+  // ]
+  console.log(top10);
+
+  // Check if a few team members are in the top 10 with TOPK.QUERY:
+  const [ steve, suze, leibale, frederick ] = await client.topK.query('mytopk', [
+    'steve',
+    'suze',
+    'leibale',
+    'frederick'
+  ]);
+
+  console.log(`steve ${steve === 1 ? 'is': 'is not'} in the top 10.`);
+  console.log(`suze ${suze === 1 ? 'is': 'is not'} in the top 10.`);
+  console.log(`leibale ${leibale === 1 ? 'is': 'is not'} in the top 10.`);
+  console.log(`frederick ${frederick === 1 ? 'is': 'is not'} in the top 10.`);
+
+  // Get count estimate for some team members:
+  const [ simonCount, lanceCount ] = await client.topK.count('mytopk', [
+    'simon',
+    'lance'
+  ]);
+
+  console.log(`Count estimate for simon: ${simonCount}.`);
+  console.log(`Count estimate for lance: ${lanceCount}.`);
+  
+  await client.quit();
+}
+
+topK();