express
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ExpressJS
Fix “Blocked by CORS Policy” in a MERN App (React + Express)
The browser blocks your React app from reading the API response because Express did not send the right CORS headers. Install the cors package and add app.use(cors({ origin: "http://localhost:5173" })) before your routes. If you send cookies, also set credentials: true on the server and credentials: "include" (or withCredentials in Axios) on the client, and never use origin "*" with credentials.
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ExpressJS
Fix “Cannot set headers after they are sent to the client” in Express
This error means your code tried to send a second response to a request that was already answered. The usual fix is to add return before res.json() or res.send() inside an if block, so the function stops after responding. Also check for next() called after a response and for callbacks that run twice.
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Backend
Building Microservices with: Complete Guide 2024 | Tutorials & Exam…
NestJS microservices use @nestjs/microservices: a service listens on a transport such as TCP, Redis, NATS or RabbitMQ, handlers use @MessagePattern for request-response and @EventPattern for fire-and-forget events, and other services call them through a ClientProxy with send() or emit(). Start with a modular monolith and split out services only when you have a clear reason.
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ExpressJS
Handling Errors in Express: Strategies for Robust Server Applications
Introduction Error handling is a crucial aspect of building robust server applications using Express.js, a popular web application framework for Node.js. Effective management of errors not only ensures…
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ExpressJS
Performance Optimization Tips for Your Express Server
Introduction Understanding Express Server Performance Optimization Importance of optimizing Express servers Common performance bottlenecks in Express applications Performance Optimization Tips for Your Express Server Tip 1: Utilize middleware…
