Understanding the TS1259 Error in TypeScriptIf you're developing a Next.js application with an Express server in TypeScript, you might encounter the TS1259 error: "Module 'express' can only be default-imported using the 'esModuleInterop' flag". This error commonly arises due to TypeScript's module resolution settings when trying to import modules from libraries like Express.What Causes TS1259?This error occurs when TypeScript attempts to use a default import where the module does not support it without the esModuleInterop flag. By default, TypeScript does not support default imports for CommonJS modules, an issue that can arise if you're integrating libraries that use this import style without the necessary configurations.Your tsconfig.json ConfigurationYou have already added the required flag in your tsconfig.json, which is great. Let's briefly review your file to ensure it includes the necessary options:{
"compilerOptions": {
"target": "es6",
"lib": ["dom", "dom.iterable", "esnext"],
"allowJs": true,
"skipLibCheck": true,
"strict": true,
"noEmit": true,
"esModuleInterop": true,
"module": "esnext",
"moduleResolution": "bundler",
"resolveJsonModule": true,
"isolatedModules": true,
"jsx": "preserve",
"incremental": true,
"plugins": [
{
"name": "next"
}
],
"paths": {
"@/*": ["./src/*"]
}
},
"include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
"exclude": ["node_modules"]
}
Double-Check Your Imports in express.ts
In your express.ts, you're importing express as a default import:import express, { Request, Response } from "express";
This is the correct way with the esModuleInterop flag enabled. However, if you've recently added this flag, you might need to restart your TypeScript compiler to ensure it picks up the new configuration.Compile and Run Your ApplicationWhen running your application, it's essential that you first compile your TypeScript files. Based on your current scripts, it looks like you're using concurrent commands to run your Electron app. Here's your package.json relevant lines:"electron:dev": "concurrently \"npm run dev\" \"npm run electron:watch\"",
"electron:watch": "tsc main.ts --outDir dist nodemon --watch main.ts --exec \"electron .\"",
Make sure that your tsc command is recognizing the latest tsconfig.json. You can compile manually by running:tsc
Step-by-Step SolutionTo resolve the TS1259 error, follow these steps:1. Ensure esModuleInterop is setMake sure that your tsconfig.json has "esModuleInterop": true included under compilerOptions.2. Restart TypeScript CompilingIf you’ve made changes to your tsconfig.json, restart your compiler to reflect those changes. This can often be done simply by closing and reopening your terminal or IDE.3. Validate Your ImportsCheck that your import statements across your project files use the correct syntax. Commonly, you should import like this:import express, { Request, Response } from "express";
4. Compile and Test Your ApplicationRun the following commands to compile and test:npm run electron:dev
Frequently Asked QuestionsWhat is esModuleInterop?esModuleInterop allows TypeScript to produce JavaScript code that can better interoperate with non-ES modules, enabling default import syntax for CommonJS modules.Do I always need this flag?If you're working extensively with modules that do not follow the ES module specification, it's generally a good idea to enable esModuleInterop.Can I manage without TypeScript?While you can create your Next.js application without TypeScript, leveraging TypeScript provides better type safety and development experience.ConclusionIn conclusion, the TS1259 error can be resolved by thoroughly validating your TypeScript configuration, ensuring imports adhere to the standard expected by TypeScript, and restarting the environment when making configuration changes. By following the outlined steps and understanding the concepts at play, you can effectively manage your Next.js and Express servers using TypeScript configurations with ease.

“You can’t sprint through a marathon — and software development is definitely a marathon.”
As developers, we love optimising things: code, queries, CI pipelines, build times. But there’s one system we often overlook — ourselves.


Time is Rigid, Energy is Fluid
Time management is a classic topic in productivity. Block calendars. Estimate sprints. Make Gantt charts. But here’s the catch: time is finite and linear. It doesn’t care how you feel. Energy, on the other hand, is your real capacity to think, decide, and create.In software development — a discipline built on deep thought, problem-solving, and clarity — energy isn’t just a nice-to-have. It’s the foundation of quality work.


The Real Productivity Multiplier: Schedule Control
The more autonomy you have over your daily schedule, the better you can align your high-energy hours with high-value tasks.That’s why the best engineers and product thinkers often don’t just ask, “What will I get done today?” but rather “When am I best able to do this kind of thinking?”If you get your best coding done between 9 AM and noon, guard that time. Schedule meetings later. If you’re more reflective after a walk or late at night, save architecture decisions or debugging sessions for then.Control over your schedule is control over your effectiveness.


Two Tie-Breakers for Your Decisions
When you’re unsure which opportunity or task to take on, try these two questions:1. Which option gives me more freedom over my time and energy?
2. Which one will teach me more?Freedom means fewer context switches, fewer urgent interruptions, and fewer downstream commitments. And learning compounds — in tech, knowledge is leverage.Even if you can’t predict the outcome of a decision, choosing the path with more autonomy and learning tends to pay off.


The Bottom 20% Rule
Let’s be honest: in your backlog, inbox, or calendar, some things simply won’t matter.When you shift from managing time to managing energy, there will be things you don’t get around to. And that’s okay. The trick is to let them go consciously, not guiltily.
Think of the last time something truly bad happened because you didn’t do a task that was in the bottom 20% of your priorities. Hard to recall, isn’t it?
Ship the feature. Skip the unnecessary retro. Answer that Slack ping tomorrow. If your mind is spent, the marginal return on doing low-priority work is worse than resting and returning with clarity.


Final Thought
Managing your energy isn’t about doing less. It’s about doing what matters better.In software, we celebrate elegant code that solves hard problems with minimal effort. It’s time we applied the same thinking to how we work — not just what we work on.