Node-RED导入现有JS库及调用全局对象的技术咨询

Hey there! Since you're new to Node-RED and Node.js, let's break this down step by step—this is actually a common scenario when moving from front-end jQuery projects to building backend APIs with Node-RED.

1. Importing Your Existing JS Files #

You have two main ways to bring in your JS library, depending on whether you want it available in a single Function node or across all nodes in your flow.

Option A: Local Import (Per Function Node) #

Node-RED's Function node supports standard Node.js require() calls, just like regular Node.js code.

• If your library is a local file (e.g., my-auth-library.js), place it in Node-RED's user directory (usually ~/.node-red on Linux/macOS, or %USERPROFILE%\.node-red on Windows).
• Then in your Function node, import it like this:

  // Import the local library
  const authLib = require('./my-auth-library.js');
  
  // Use it in your logic
  const isValidUser = authLib.validateCredentials(msg.payload.username, msg.payload.password);
  msg.payload = { success: isValidUser };
  return msg;
  

• If your library is an npm package, first install it in Node-RED's user directory via terminal:

  cd ~/.node-red
  npm install your-package-name
  

  Then import it the same way: const authLib = require('your-package-name');

Option B: Global Import (All Function Nodes) #

If you want your library accessible everywhere in your Node-RED instance, configure it in the settings.js file:

1. Open settings.js (located in your Node-RED user directory).
2. Find the functionGlobalContext section, uncomment it, and add your library:

   functionGlobalContext: {
       // Import local file
       authLib: require('./my-auth-library.js'),
       // Or an npm package
       jwt: require('jsonwebtoken')
   },
   

3. Restart Node-RED to apply the changes.
4. Now in any Function node, access it using global.get():

   const authLib = global.get('authLib');
   const sessionToken = authLib.generateToken(msg.payload.userId);
   msg.payload = { token: sessionToken };
   return msg;
   

2. Calling Library Functions & Creating Global Objects #

Calling Library Functions #

Once you've imported the library, calling its functions works exactly like you'd expect in regular JS. For example, if your library has a login() function:

// Local import example
const authLib = require('./my-auth-library.js');
const loginResult = authLib.login(msg.payload.username, msg.payload.password);

// Global import example
const authLib = global.get('authLib');
const logoutSuccess = authLib.logout(msg.payload.token);

Creating Globally Accessible Objects #

If you need an object (like a session manager or config store) to be available across all nodes, use Node-RED's global context:

1. Initialize the object in a Function node (maybe a "Start" node that runs once on flow deploy):

   const authLib = global.get('authLib');
   // Create your global object
   const sessionManager = authLib.createSessionStore();
   // Save it to global context
   global.set('sessionManager', sessionManager);
   

2. Then in any other Function node, retrieve and use it:

   const sessionManager = global.get('sessionManager');
   const userSession = sessionManager.getSession(msg.payload.token);
   msg.payload = { user: userSession };
   return msg;
   

Note: By default, global context uses in-memory storage—so your objects will reset if Node-RED restarts. If you need persistent storage, you can configure context storage in settings.js (look for the contextStorage section).

Quick Tips for Your Login/Logout API #

• For your HTTP In nodes listening to POST requests, connect them to Function nodes where you'll use your library to handle authentication logic.
• If your library uses asynchronous functions (like database calls), use async/await in your Function node to handle them properly:

  async function handleLogin(msg) {
      const authLib = global.get('authLib');
      // Await the async login function
      const loginResult = await authLib.asyncLogin(msg.payload.username, msg.payload.password);
      msg.payload = loginResult;
      return msg;
  }
  return handleLogin(msg);
  

内容的提问来源于stack exchange，提问作者Vladimir B