我把一些langchain代码放到一个托管的node.js服务器上，我不知道把我的OpenAPI API密钥放在哪里

const http = require('http');
const cors = require("cors");
const { OpenAI } = require("langchain/llms/openai");

const { PDFLoader } = require("langchain/document_loaders/fs/pdf");
const { FaissStore } = require("langchain/vectorstores/faiss");
const { OpenAIEmbeddings } = require("langchain/embeddings/openai");
const { RecursiveCharacterTextSplitter } = require('langchain/text_splitter');

const fs = require('fs');

OpenAI.api_key = '12345.....'

const processSteps = async () => {
// Step One
const loader = new PDFLoader("documents/document.pdf");
const docs = await loader.load();

// Step Two
const textSplitter = new RecursiveCharacterTextSplitter({
chunkSize: 1000,
chunkOverlap: 200,
});

// Step Three
const docOutput = await textSplitter.splitDocuments(docs)
let vectorStore = await FaissStore.fromDocuments(docOutput, new OpenAIEmbeddings());

// Step Four
const directory = "documents";
await vectorStore.save(directory);
}

http.createServer(async function(req, res) {
var ret = "Start"
try {
await processSteps();
ret = "All steps completed successfully";
} catch (error) {
console.error('An error occurred:', error);
ret = "An error occurred: " + error;
}

res.writeHead(200, {
'Content-Type': 'text/plain'
});
res.end(ret);
}).listen(process.env.PORT);

当我运行代码时，

An error occurred: Error: OpenAI or Azure OpenAI API key not found

如果我把代码写在
Run OpenAI API document example in Node: where do I put sample code?

const configuration = new Configuration({      
    apiKey: '12345.....',
});
const openai = new OpenAIApi(configuration);

我得到

TypeError: Configuration is not a constructor