Which Language When and Why?

// Async fetch with error handling
async function getUserProfile(userId: string) {
  try {
    const res = await fetch(`/api/users/${userId}`, {
      cache: 'no-store' // Always fresh data
    });
    if (!res.ok) throw new Error(`HTTP error! status: ${res.status}`);
    return await res.json();
  } catch (error) {
    console.error("Fetch failed:", error);
    return null;
  }
}

// Type-safe PostgreSQL query
import { prisma } from '@/lib/db';

export async function getActiveUsers() {
  return await prisma.user.findMany({
    where: { isActive: true },
    select: { id: true, name: true, email: true },
    orderBy: { createdAt: 'desc' },
    take: 10
  });
}

import { SignJWT, jwtVerify } from 'jose';

const secret = new TextEncoder().encode(process.env.JWT_SECRET!);

// Sign a secure JWT Token
export async function createToken(payload: { userId: string }) {
  return await new SignJWT(payload)
    .setProtectedHeader({ alg: 'HS256' })
    .setExpirationTime('2h')
    .sign(secret);
}

import { create } from 'zustand';

interface CartState {
  items: string[];
  addItem: (item: string) => void;
  clearCart: () => void;
}

export const useCartStore = create<CartState>((set) => ({
  items: [],
  addItem: (item) => set((state) => ({ items: [...state.items, item] })),
  clearCart: () => set({ items: [] }),
}));

package main

import "github.com/gofiber/fiber/v2"

func main() {
    app := fiber.New()

    // Responds in ~0.9 milliseconds
    app.Get("/api/ping", func(c *fiber.Ctx) error {
        return c.JSON(fiber.Map{"status": "ok", "speed": "ultra-fast"})
    })

    app.Listen(":3000")
}

# .env.local
DATABASE_URL="postgresql://user:pass@localhost:5432/mydb"
JWT_SECRET="super-secret-key-do-not-share"
NEXT_PUBLIC_API_URL="https://devcompass.app" # Safe for client browser

// In code (Server-Side only):
const dbUrl = process.env.DATABASE_URL;