#2285-Add-example-scripts-hyperloglog - Added hyperloglog examples to… (#2289)

* #2285-Add-example-scripts-hyperloglog - Added hyperloglog examples to address Issue #2285

* #2285-Add-example-scripts-hyperloglog - Added the results as comments

* #2285-Add-example-scripts-hyperloglog - Changes from review

* #2285-Add-example-scripts-hyperloglog - Changes from review

Author: ade1705

examples/README.md

@@ -11,6 +11,7 @@ This folder contains example scripts showing how to use Node Redis in different
 | `count-min-sketch.js`       | Estimate the frequency of a given event using the [RedisBloom](https://redisbloom.io) Count-Min Sketch                                              |
 | `cuckoo-filter.js`          | Space efficient set membership checks with a [Cuckoo Filter](https://en.wikipedia.org/wiki/Cuckoo_filter) using [RedisBloom](https://redisbloom.io) |
 | `get-server-time.js`        | Get the time from the Redis server                                                                                                                  |
+| `hyperloglog.js`            | Showing use of Hyperloglog commands [PFADD, PFCOUNT and PFMERGE](https://redis.io/commands/?group=hyperloglog)                                |
 | `lua-multi-incr.js`         | Define a custom lua script that allows you to perform INCRBY on multiple keys                                                                       |
 | `managing-json.js`          | Store, retrieve and manipulate JSON data atomically with [RedisJSON](https://redisjson.io/)                                                         |
 | `search-hashes.js`          | Uses [RediSearch](https://redisearch.io) to index and search data in hashes                                                                         |

examples/hyperloglog.js

@@ -0,0 +1,51 @@
+// Example to log traffic data at intersections for the city of San Francisco.
+// Log license plates of each car scanned at each intersection and add to the intersections Hyperloglog.
+// Reference: https://www.youtube.com/watch?v=MunL8nnwscQ
+
+import { createClient } from 'redis';
+
+const client = createClient();
+
+await client.connect();
+
+// Use `pfAdd` to add an element to a Hyperloglog, creating the Hyperloglog if necessary.
+// await client.pfAdd(key, value)
+
+// To get a count, the `pfCount` method is used.
+// await client.pfCount(key)
+
+try {
+  // Corner of Market Street (ID: 12) and 10th street (ID:27).
+  await client.pfAdd('count:sf:12:27', 'GHN34X');
+  await client.pfAdd('count:sf:12:27', 'ECN94Y');
+  await client.pfAdd('count:sf:12:27', 'VJL12V');
+  await client.pfAdd('count:sf:12:27', 'ORV87O');
+
+  // To get the count of Corner of Market Street (ID: 12) and 10th street (ID:27).
+  const countForMarket10thStreet = await client.pfCount('count:sf:12:27');
+  console.log(`Count for Market Street & 10th Street is ${countForMarket10thStreet}`);
+  // Count for Market Street & 10th Street is 4.
+
+  // Corner of Market Street (ID: 12) and 11 street (ID:26).
+  await client.pfAdd('count:sf:12:26', 'GHN34X');
+  await client.pfAdd('count:sf:12:26', 'ECN94Y');
+  await client.pfAdd('count:sf:12:26', 'IRV84E');
+  await client.pfAdd('count:sf:12:26', 'ORV87O');
+  await client.pfAdd('count:sf:12:26', 'TEY34S');
+
+  // To get the count of Corner of Market Street (ID: 12) and 11th street (ID:26).
+  const countForMarket11thStreet = await client.pfCount('count:sf:12:26');
+  console.log(`Count for Market Street & 11th Street is ${countForMarket11thStreet}`);
+  // Count for Market Street & 11th Street is 5.
+
+  // To merge the Hyperloglogs `count:sf:12:26` and `count:sf:12:27`.
+  await client.pfMerge('count:merge', ['count:sf:12:27', 'count:sf:12:26']);
+  const countMerge = await client.pfCount('count:merge');
+  console.log(`Count for the merge is ${countMerge}`);
+  // Count for the merge is 6.
+} catch (e) {
+  // something went wrong.
+  console.error(e);
+}
+
+await client.quit();