add streaming examples

examples/js/streamMessages.js

@@ -0,0 +1,89 @@
+import { Client } from "@langchain/langgraph-sdk";
+
+/*
+There are multiple different streaming modes.
+
+- values: This streaming mode streams back values of the graph. This is the full state of the graph after each node is called.
+- updates: This streaming mode streams back updates to the graph. This is the update to the state of the graph after each node is called.
+- messages: This streaming mode streams back messages - both complete messages (at the end of a node) as well as tokens for any messages generated inside a node. This mode is primarily meant for powering chat applications.
+
+This script covers streaming_mode="messages".
+
+In order to use this mode, the state of the graph you are interacting with MUST have a messages key that is a list of messages. Eg, the state should look something like:
+
+from typing import TypedDict, Annotated
+from langgraph.graph import add_messages
+from langchain_core.messages import AnyMessage
+
+class State(TypedDict):
+    messages: Annotated[list[AnyMessage], add_messages]
+
+    OR it should be an instance or subclass of from langgraph.graph import MessageState (MessageState is just a helper type hint equivalent to the above).
+
+With stream_mode="messages" two things will be streamed back:
+
+It outputs messages produced by any chat model called inside (unless tagged in a special way)
+It outputs messages returned from nodes (to allow for nodes to return ToolMessages and the like
+*/
+
+async function streamMessages() {
+  const client = new Client();
+  const assistant = await client.assistants.create({ graphId: "agent", config: { configurable: { model_name: "openai" } }});
+  console.log("Assistant", assistant);
+
+  const thread = await client.threads.create({ metadata: null });
+  console.log("Thread", thread);
+
+  const runs = await client.runs.list(thread.thread_id);
+  console.log("Runs", runs);
+
+  // Helper function for formatting messages
+  function formatToolCalls(toolCalls) {
+    if (toolCalls && toolCalls.length > 0) {
+      const formattedCalls = toolCalls.map(call => `Tool Call ID: ${call.id}, Function: ${call.name}, Arguments: ${JSON.stringify(call.args)}`);
+      return formattedCalls.join("\n");
+    }
+    return "No tool calls";
+  }
+
+  const input = { messages: [{ role: "user", content: "whats the weather in sf" }] };
+
+  for await (const event of client.runs.stream(thread.thread_id, assistant.assistant_id, { input, streamMode: "messages" })) {
+    if (event.event === "metadata") {
+      console.log(`Metadata: Run ID - ${event.data["run_id"]}`);
+    } else if (event.event === "messages/partial") {
+      for (const dataItem of event.data) {
+        if ("role" in dataItem && dataItem.role === "user") {
+          console.log(`Human: ${dataItem.content}`);
+        } else {
+          const toolCalls = dataItem.tool_calls || [];
+          const invalidToolCalls = dataItem.invalid_tool_calls || [];
+          const content = dataItem.content || "";
+          const responseMetadata = dataItem.response_metadata || {};
+
+          if (content) {
+            console.log(`AI: ${content}`);
+          }
+
+          if (toolCalls.length > 0) {
+            console.log("Tool Calls:");
+            console.log(formatToolCalls(toolCalls));
+          }
+
+          if (invalidToolCalls.length > 0) {
+            console.log("Invalid Tool Calls:");
+            console.log(formatToolCalls(invalidToolCalls));
+          }
+
+          if (responseMetadata) {
+            const finishReason = responseMetadata.finish_reason || "N/A";
+            console.log(`Response Metadata: Finish Reason - ${finishReason}`);
+          }
+        }
+      }
+      console.log("-".repeat(50));
+    }
+  }
+}
+  
+streamMessages()

examples/js/streamUpdates.js

@@ -0,0 +1,33 @@
+import { Client } from "@langchain/langgraph-sdk";
+
+/*
+There are multiple different streaming modes.
+
+- values: This streaming mode streams back values of the graph. This is the full state of the graph after each node is called.
+- updates: This streaming mode streams back updates to the graph. This is the update to the state of the graph after each node is called.
+- messages: This streaming mode streams back messages - both complete messages (at the end of a node) as well as tokens for any messages generated inside a node. This mode is primarily meant for powering chat applications.
+
+This script covers streaming_mode="updates".
+*/
+
+async function streamUpdates() {
+  const client = new Client();
+  const assistant = await client.assistants.create({ graphId: "agent", config: { configurable: { model_name: "openai" } }});
+  console.log("Assistant", assistant);
+
+  const thread = await client.threads.create({ metadata: null });
+  console.log("Thread", thread);
+
+  const runs = await client.runs.list(thread.thread_id);
+  console.log("Runs", runs);
+
+  const input = { messages: [{ role: "user", content: "whats the weather in sf" }] };
+
+  for await (const event of client.runs.stream(thread.thread_id, assistant.assistant_id, { input, streamMode: "updates" })) {
+    console.log(`Receiving new event of type: ${event.event}...`);
+    console.log(JSON.stringify(event.data));
+    console.log("\n\n");
+  }
+}
+
+streamUpdates()