Creating a ReAct Agent from the scratch with nodeJS ( wikipedia search )

mkdir react-agent-project
cd react-agent-project
npm init -y
npm install axios dotenv @google/generative-ai

GOOGLE_AI_API_KEY=your_api_key_here

const axios = require("axios");

class Tools {
  static async wikipedia(q) {
    try {
      const response = await axios.get("https://en.wikipedia.org/w/api.php", {
        params: {
          action: "query",
          list: "search",
          srsearch: q,
          srwhat: "text",
          format: "json",
          srlimit: 4,
        },
      });

      const results = await Promise.all(
        response.data.query.search.map(async (searchResult) => {
          const sectionResponse = await axios.get(
            "https://en.wikipedia.org/w/api.php",
            {
              params: {
                action: "parse",
                pageid: searchResult.pageid,
                prop: "sections",
                format: "json",
              },
            },
          );

          const sections = Object.values(
            sectionResponse.data.parse.sections,
          ).map((section) => `${section.index}, ${section.line}`);

          return {
            pageTitle: searchResult.title,
            snippet: searchResult.snippet,
            pageId: searchResult.pageid,
            sections: sections,
          };
        }),
      );

      return results
        .map(
          (result) =>
            `Snippet: ${result.snippet}\nPageId: ${result.pageId}\nSections: ${JSON.stringify(result.sections)}`,
        )
        .join("\n\n");
    } catch (error) {
      console.error("Error fetching from Wikipedia:", error);
      return "Error fetching data from Wikipedia";
    }
  }

  static async wikipedia_with_pageId(pageId, sectionId) {
    if (sectionId) {
      const response = await axios.get("https://en.wikipedia.org/w/api.php", {
        params: {
          action: "parse",
          format: "json",
          pageid: parseInt(pageId),
          prop: "wikitext",
          section: parseInt(sectionId),
          disabletoc: 1,
        },
      });
      return Object.values(response.data.parse?.wikitext ?? {})[0]?.substring(
        0,
        25000,
      );
    } else {
      const response = await axios.get("https://en.wikipedia.org/w/api.php", {
        params: {
          action: "query",
          pageids: parseInt(pageId),
          prop: "extracts",
          exintro: true,
          explaintext: true,
          format: "json",
        },
      });
      return Object.values(response.data?.query.pages)[0]?.extract;
    }
  }
}

module.exports = Tools;

require("dotenv").config();
const { GoogleGenerativeAI } = require("@google/generative-ai");
const Tools = require("./Tools");

const genAI = new GoogleGenerativeAI(process.env.GOOGLE_AI_API_KEY);

class ReActAgent {
  constructor(query, functions) {
    this.query = query;
    this.functions = new Set(functions);
    this.state = "THOUGHT";
    this._history = [];
    this.model = genAI.getGenerativeModel({
      model: "gemini-1.5-flash",
      temperature: 2,
    });
  }

  get history() {
    return this._history;
  }

  pushHistory(value) {
    this._history.push(`\n ${value}`);
  }

  async run() {
    this.pushHistory(`**Task: ${this.query} **`);
    try {
      return await this.step();
    } catch (e) {
      if (e.message.includes("exhausted")) {
        return "Sorry, I'm exhausted, I can't process your request anymore. ><";
      }
      return "Unable to process your request, please try again? ><";
    }
  }

  async step() {
    const colors = {
      reset: "\x1b[0m",
      yellow: "\x1b[33m",
      red: "\x1b[31m",
      cyan: "\x1b[36m",
    };

    console.log("====================================");
    console.log(
      `Next Movement: ${
        this.state === "THOUGHT"
          ? colors.yellow
          : this.state === "ACTION"
            ? colors.red
            : this.state === "ANSWER"
              ? colors.cyan
              : colors.reset
      }${this.state}${colors.reset}`,
    );
    console.log(`Last Movement: ${this.history[this.history.length - 1]}`);
    console.log("====================================");
    switch (this.state) {
      case "THOUGHT":
        await this.thought();
        break;
      case "ACTION":
        await this.action();
        break;
      case "ANSWER":
        await this.answer();
        break;
    }
  }

  async promptModel(prompt) {
    const result = await this.model.generateContent(prompt);
    const response = await result.response;
    return response.text();
  }

  async thought() {
    const availableFunctions = JSON.stringify(Array.from(this.functions));
    const historyContext = this.history.join("\n");
    const prompt = `Your task to FullFill ${this.query}.
Context contains all the reflection you made so far and the ActionResult you collected.
AvailableActions are functions you can call whenever you need more data.

Context: "${historyContext}" <<

AvailableActions: "${availableFunctions}" <<

Task: "${this.query}" <<

Reflect uppon Your Task using Context, ActionResult and AvailableActions to find your next_step.
print your next_step with a Thought or FullFill Your Task `;

    const thought = await this.promptModel(prompt);
    this.pushHistory(`\n **${thought.trim()}**`);
    if (
      thought.toLowerCase().includes("fullfill") ||
      thought.toLowerCase().includes("fulfill")
    ) {
      this.state = "ANSWER";
      return await this.step();
    }
    this.state = "ACTION";
    return await this.step();
  }

  async action() {
    const action = await this.decideAction();
    this.pushHistory(`** Action: ${action} **`);
    const result = await this.executeFunctionCall(action);
    this.pushHistory(`** ActionResult: ${result} **`);
    this.state = "THOUGHT";
    return await this.step();
  }

  async decideAction() {
    const availableFunctions = JSON.stringify(Array.from(this.functions));
    const historyContext = this.history;
    const prompt = `Reflect uppon the Thought, Query and AvailableActions

    ${historyContext[historyContext.length - 2]}

    Thought <<< ${historyContext[historyContext.length - 1]}

    Query: "${this.query}"

    AvailableActions: ${availableFunctions}

    output only the function,parametervalues separated by a comma. For example: "wikipedia,ronaldinho gaucho, 1450"`;

    const decision = await this.promptModel(prompt);
    return `${decision.replace(/`/g, "").trim()}`;
  }

  async executeFunctionCall(functionCall) {
    const [functionName, ...args] = functionCall.split(",");
    const func = Tools[functionName.trim()];
    if (func) {
      return await func.call(null, ...args);
    }
    throw new Error(`Function ${functionName} not found`);
  }

  async answer() {
    const historyContext = this.history;
    const prompt = `Based on the following context, provide a complete, detailed and descriptive formated answer for the Following Task: ${this.query} .

Context:
${historyContext}

Task: "${this.query}"`;

    const finalAnswer = await this.promptModel(prompt);
    this.history.push(`Answer: ${this.finalAnswer}`);
    console.log("WE WILL ANSWER >>>>>>>", finalAnswer);
    return finalAnswer;
  }
}

module.exports = ReActAgent;

const ReActAgent = require("./ReactAgent.js");

async function main() {
  const query = "What does England border with?";
  const functions = [
    [
      "wikipedia",
      "params: query",
      "Semantic Search Wikipedia API for snippets, pageIds and sectionIds >> \n ex: Date brazil has been colonized? \n Brazil was colonized at 1500, pageId, sections : []",
    ],
    [
      "wikipedia_with_pageId",
      "params : pageId, sectionId",
      "Search Wikipedia API for data using a pageId and a sectionIndex as params.  \n ex: 1500, 1234 \n Section information about blablalbal",
    ],
  ];

  const agent = new ReActAgent(query, functions);
  try {
    const result = await agent.run();
    console.log("THE AGENT RETURN THE FOLLOWING >>>", result);
  } catch (e) {
    console.log("FAILED TO RUN T.T", e);
  }
}

main().catch(console.error);