The gist of it

.gitignore

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+config/

Dockerfile

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+FROM node:latest
+
+WORKDIR /app
+#RUN npm init es6 -y
+RUN npm install typescript
+RUN npm install -D ts-node
+RUN npm install @types/node
+RUN npm install langchain
+RUN npm install openai
+RUN npm install dotenv
+
+RUN npm i
+
+COPY config/env ./.env
+COPY server/ /app
+RUN npm run build
+
+CMD ["npm", "run", "start"]

README.md

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+ChatGPT & langchain example for node.js
+=======================================
+
+This repository contains containerized code from [this tutorial](https://langchainers.hashnode.dev/getting-started-with-langchainjs) modified to use the ChatGPT language model, trained by OpenAI, into a node.js project using [LangChain.js](https://github.com/hwchase17/langchainjs), an API for language models.
+
+Getting started
+To use this code, you will need to have a OpenAI API key. If you don't have one yet, you can get one by signing up at https://platform.openai.com
+
+Once you have your API key, clone this repository and add the following with your key to `config/env`':
+
+```
+OPENAI_API_KEY={YOUR_API_KEY}
+```
+
+After this you can test it by building and running with:
+
+```
+docker build -t langchain_example . 
+docker run -it langchain_example
+```

server/package.json

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+{
+  "name": "",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "type": "module",
+  "license": "AGPL-version-3.0",
+  "private": false,
+  "engines": {
+    "node": ">= 14.0.0",
+    "npm": ">= 6.0.0"
+  },
+  "homepage": "",
+  "repository": {
+    "type": "git",
+    "url": ""
+  },
+  "bugs": "",
+  "keywords": [],
+  "author": {
+    "name": "",
+    "email": "",
+    "url": ""
+  },
+  "contributors": [],
+  "scripts": { 
+    "build": "tsc", 
+    "start": "node ./dist/app.js", 
+    "dev": "ts-node --esm ./src/app.ts"
+  },
+
+  "dependencies": {
+    "@types/node": "^18.14.6",
+    "cors": "^2.8.5",
+    "express": "^4.18.2",
+    "formidable": "^3.2.5",
+    "md5": "^2.3.0",
+    "typescript": "^4.9.5"
+  },
+  "devDependencies": {
+    "ts-node": "^10.9.1"
+  }
+}

server/src/app.ts

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+//Import the OpenAPI Large Language Model (you can import other models here eg. Cohere)
+import { OpenAIChat } from "langchain/llms";
+
+//Import the BufferMemory module
+import { BufferMemory } from "langchain/memory";
+
+//Import the Chains module
+import { LLMChain } from "langchain/chains";
+
+//Import the PromptTemplate module
+import { PromptTemplate } from "langchain/prompts";
+
+//Load environment variables (populate process.env from .env file)
+import * as dotenv from "dotenv";
+dotenv.config();
+
+export const run = async () => {
+
+  //Instantiate the BufferMemory passing the memory key for storing state 
+  const memory = new BufferMemory({ memoryKey: "chat_history" });
+
+  //Instantiante the OpenAI model 
+  //Pass the "temperature" parameter which controls the RANDOMNESS of the model's output. A lower temperature will result in more predictable output, while a higher temperature will result in more random output. The temperature parameter is set between 0 and 1, with 0 being the most predictable and 1 being the most random
+  const model = new OpenAIChat({ temperature: 0.9 });
+
+  //Create the template. The template is actually a "parameterized prompt". A "parameterized prompt" is a prompt in which the input parameter names are used and the parameter values are supplied from external input 
+  //Note the input variables {chat_history} and {input}
+  const template = `The following is a friendly conversation between a human and an AI. The AI is talkative and provides lots of specific details from its context. If the AI does not know the answer to a question, it truthfully says it does not know. The AI answers as Yoda.
+  Current conversation:
+  {chat_history}
+  Human: {input}
+  AI:`;
+
+  //Instantiate "PromptTemplate" passing the prompt template string initialized above
+  const prompt = PromptTemplate.fromTemplate(template);
+
+  //Instantiate LLMChain, which consists of a PromptTemplate, an LLM and memory. 
+  const chain = new LLMChain({ llm: model, prompt, memory });
+
+  //Run the chain passing a value for the {input} variable. The result will be stored in {chat_history}
+  const res1 = await chain.call({ input: "Hi! I'm Morpheus." });
+  console.log({ res1 });
+
+  //Run the chain again passing a value for the {input} variable. This time, the response from the last run ie. the  value in {chat_history} will alo be passed as part of the prompt
+  const res2 = await chain.call({ input: "What's my name?" });
+  console.log({ res2 });
+
+  //BONUS!!
+  const res3 = await chain.call({ input: "Which epic movie was I in and who was my protege?" });
+  console.log({ res3 });
+  };
+
+run();

server/tsconfig.json

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+{
+  "compilerOptions": {
+    /* Visit https://aka.ms/tsconfig to read more about this file */
+
+    /* Projects */
+    // "incremental": true,                              /* Save .tsbuildinfo files to allow for incremental compilation of projects. */
+    // "composite": true,                                /* Enable constraints that allow a TypeScript project to be used with project references. */
+    // "tsBuildInfoFile": "./.tsbuildinfo",              /* Specify the path to .tsbuildinfo incremental compilation file. */
+    // "disableSourceOfProjectReferenceRedirect": true,  /* Disable preferring source files instead of declaration files when referencing composite projects. */
+    // "disableSolutionSearching": true,                 /* Opt a project out of multi-project reference checking when editing. */
+    // "disableReferencedProjectLoad": true,             /* Reduce the number of projects loaded automatically by TypeScript. */
+
+    /* Language and Environment */
+    "target": "es2020",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
+    "lib": ["es2020"],                                   /* Specify a set of bundled library declaration files that describe the target runtime environment. */
+    // "jsx": "preserve",                                /* Specify what JSX code is generated. */
+    // "experimentalDecorators": true,                   /* Enable experimental support for TC39 stage 2 draft decorators. */
+    // "emitDecoratorMetadata": true,                    /* Emit design-type metadata for decorated declarations in source files. */
+    // "jsxFactory": "",                                 /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h'. */
+    // "jsxFragmentFactory": "",                         /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
+    // "jsxImportSource": "",                            /* Specify module specifier used to import the JSX factory functions when using 'jsx: react-jsx*'. */
+    // "reactNamespace": "",                             /* Specify the object invoked for 'createElement'. This only applies when targeting 'react' JSX emit. */
+    // "noLib": true,                                    /* Disable including any library files, including the default lib.d.ts. */
+    // "useDefineForClassFields": true,                  /* Emit ECMAScript-standard-compliant class fields. */
+    // "moduleDetection": "auto",                        /* Control what method is used to detect module-format JS files. */
+
+    /* Modules */
+    "module": "nodenext",                                /* Specify what module code is generated. */
+    "rootDir": "src",                                    /* Specify the root folder within your source files. */
+    // "moduleResolution": "node",                       /* Specify how TypeScript looks up a file from a given module specifier. */
+    // "baseUrl": "./",                                  /* Specify the base directory to resolve non-relative module names. */
+    // "paths": {},                                      /* Specify a set of entries that re-map imports to additional lookup locations. */
+    // "rootDirs": [],                                   /* Allow multiple folders to be treated as one when resolving modules. */
+    // "typeRoots": [],                                  /* Specify multiple folders that act like './node_modules/@types'. */
+    // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
+    // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
+    // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "resolveJsonModule": true,                        /* Enable importing .json files. */
+    // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
+
+    /* JavaScript Support */
+    // "allowJs": true,                                  /* Allow JavaScript files to be a part of your program. Use the 'checkJS' option to get errors from these files. */
+    // "checkJs": true,                                  /* Enable error reporting in type-checked JavaScript files. */
+    // "maxNodeModuleJsDepth": 1,                        /* Specify the maximum folder depth used for checking JavaScript files from 'node_modules'. Only applicable with 'allowJs'. */
+
+    /* Emit */
+    // "declaration": true,                              /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
+    // "declarationMap": true,                           /* Create sourcemaps for d.ts files. */
+    // "emitDeclarationOnly": true,                      /* Only output d.ts files and not JavaScript files. */
+    // "sourceMap": true,                                /* Create source map files for emitted JavaScript files. */
+    // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
+    "outDir": "./dist",                                  /* Specify an output folder for all emitted files. */
+    // "removeComments": true,                           /* Disable emitting comments. */
+    // "noEmit": true,                                   /* Disable emitting files from a compilation. */
+    // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
+    // "importsNotUsedAsValues": "remove",               /* Specify emit/checking behavior for imports that are only used for types. */
+    // "downlevelIteration": true,                       /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
+    // "sourceRoot": "",                                 /* Specify the root path for debuggers to find the reference source code. */
+    // "mapRoot": "",                                    /* Specify the location where debugger should locate map files instead of generated locations. */
+    // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
+    // "inlineSources": true,                            /* Include source code in the sourcemaps inside the emitted JavaScript. */
+    // "emitBOM": true,                                  /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
+    // "newLine": "crlf",                                /* Set the newline character for emitting files. */
+    // "stripInternal": true,                            /* Disable emitting declarations that have '@internal' in their JSDoc comments. */
+    // "noEmitHelpers": true,                            /* Disable generating custom helper functions like '__extends' in compiled output. */
+    // "noEmitOnError": true,                            /* Disable emitting files if any type checking errors are reported. */
+    // "preserveConstEnums": true,                       /* Disable erasing 'const enum' declarations in generated code. */
+    // "declarationDir": "./",                           /* Specify the output directory for generated declaration files. */
+    // "preserveValueImports": true,                     /* Preserve unused imported values in the JavaScript output that would otherwise be removed. */
+
+    /* Interop Constraints */
+    // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
+    // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
+    "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
+    // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
+    "forceConsistentCasingInFileNames": true,            /* Ensure that casing is correct in imports. */
+
+    /* Type Checking */
+    "strict": true,                                      /* Enable all strict type-checking options. */
+    "noImplicitAny": true,                               /* Enable error reporting for expressions and declarations with an implied 'any' type. */
+    // "strictNullChecks": true,                         /* When type checking, take into account 'null' and 'undefined'. */
+    // "strictFunctionTypes": true,                      /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */
+    // "strictBindCallApply": true,                      /* Check that the arguments for 'bind', 'call', and 'apply' methods match the original function. */
+    // "strictPropertyInitialization": true,             /* Check for class properties that are declared but not set in the constructor. */
+    // "noImplicitThis": true,                           /* Enable error reporting when 'this' is given the type 'any'. */
+    // "useUnknownInCatchVariables": true,               /* Default catch clause variables as 'unknown' instead of 'any'. */
+    // "alwaysStrict": true,                             /* Ensure 'use strict' is always emitted. */
+    // "noUnusedLocals": true,                           /* Enable error reporting when local variables aren't read. */
+    // "noUnusedParameters": true,                       /* Raise an error when a function parameter isn't read. */
+    // "exactOptionalPropertyTypes": true,               /* Interpret optional property types as written, rather than adding 'undefined'. */
+    // "noImplicitReturns": true,                        /* Enable error reporting for codepaths that do not explicitly return in a function. */
+    // "noFallthroughCasesInSwitch": true,               /* Enable error reporting for fallthrough cases in switch statements. */
+    // "noUncheckedIndexedAccess": true,                 /* Add 'undefined' to a type when accessed using an index. */
+    // "noImplicitOverride": true,                       /* Ensure overriding members in derived classes are marked with an override modifier. */
+    // "noPropertyAccessFromIndexSignature": true,       /* Enforces using indexed accessors for keys declared using an indexed type. */
+    // "allowUnusedLabels": true,                        /* Disable error reporting for unused labels. */
+    // "allowUnreachableCode": true,                     /* Disable error reporting for unreachable code. */
+
+    /* Completeness */
+    // "skipDefaultLibCheck": true,                      /* Skip type checking .d.ts files that are included with TypeScript. */
+    "skipLibCheck": true                                 /* Skip type checking all .d.ts files. */
+  }
+}