docs: add examples for xrange and xadd

Author: luin

examples/stream.js

@@ -1,7 +1,9 @@
 const Redis = require("ioredis");
 const redis = new Redis();
+const sub = new Redis();
 const pub = new Redis();
 
+// Usage 1: As message hub
 const processMessage = (message) => {
   console.log("Id: %s. Data: %O", message[0], message[1]);
 };
@@ -10,13 +12,7 @@ async function listenForMessage(lastId = "$") {
   // `results` is an array, each element of which corresponds to a key.
   // Because we only listen to one key (mystream) here, `results` only contains
   // a single element. See more: https://redis.io/commands/xread#return-value
-  const results = await redis.xread(
-    "BLOCK",
-    0,
-    "STREAMS",
-    "user-stream",
-    lastId
-  );
+  const results = await sub.xread("BLOCK", 0, "STREAMS", "user-stream", lastId);
   const [key, messages] = results[0]; // `key` equals to "user-stream"
 
   messages.forEach(processMessage);
@@ -32,3 +28,22 @@ setInterval(() => {
   // so we use another connection to publish messages.
   pub.xadd("user-stream", "*", "name", "John", "age", "20");
 }, 1000);
+
+// Usage 2: As a list
+async function main() {
+  redis
+    .pipeline()
+    .xadd("list-stream", "*", "id", "item1")
+    .xadd("list-stream", "*", "id", "item2")
+    .xadd("list-stream", "*", "id", "item3")
+    .exec();
+
+  const items = await redis.xrange("list-stream", "-", "+", "COUNT", 2);
+  console.log(items);
+  // [
+  //   [ '1647321710097-0', [ 'id', 'item1' ] ],
+  //   [ '1647321710098-0', [ 'id', 'item2' ] ]
+  // ]
+}
+
+main();