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Javascript – Why does React show type errors in the browser while Next.js does not?

I’m working with both React and Next.js using TypeScript, and I noticed a difference in how they handle type errors.

In a React project, if there’s a type mismatch or TypeScript error, the error is immediately shown in the browser, which helps me catch issues early. However, in a Next.js project, even when there are type errors, they don’t appear in the browser during development.

Can someone explain why this behavior is different between React and Next.js? Is there any setting or configuration in Next.js that can make it behave the same way as React regarding TypeScript errors?

I would appreciate any insights or suggestions!

export default function Home() {
    let a: number = 123;
    a = "12123";

        retrun(...)
}

In Next.js, the above code does not trigger an error in the browser, but in React, it does.

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2

Answers


  1. 0

    Type errors are displayed in the browser during rendering by React, although they might not be as noticeable in Next.js because of:

    1. SSR Action: Subsequent.Because server-side rendering is used by JavaScript, type mistakes that appear solely during client-side hydration can be hidden.

    2. TypeScript Handling: TypeScript is supported natively by Next.js, which suppresses some errors and concentrates more on build-time checks.

    3. Development Mode: Compared to React, which displays all faults instantly in the browser during development, Next.js may display less problems in production.

    Use rigorous TypeScript settings and run TypeScript checks frequently in both frameworks to detect all type issues.

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  2. 0

    It is due to how Next.js handles Typescript and its build process.
    In Next.js, there are a few reasons:

    1.Server-Side Rendering: this sometimes lead to type errors not being immediately visible in the browser since the code may execute without being fully type-checked in the same way as in a client-rendered React app.
    2.Type Checking Behavior: If you’re running the development server with next dev, TypeScript errors might not break the development server but will show up in the terminal where the Next.js process is running.
    3.Typescript Configuration: Just ensure that in tsconfig.json the strict option is enabled, which will enforce stricter type checks throughout your application.
    4.Next.js Type Checking: enable type checking using the next dev command by adding the –type-check flag, however this may not be the default behavior..

    The way to enable type errors in Next.js

    1. tsconfig.json:
      {
      "compilerOptions": {
      "strict": true,
      // other options
      }
      }
    2. Run Type Checking During Development:
      npx next build && npx next dev
    3. The change in the package.json:
      "scripts": {
      "dev": "next dev",
      "type-check": "tsc –noEmit",
      "dev:check": "concurrently "npm run dev" "npm run type-check""
      }
      for this, u will need to install concurrently to run both commands simultaneously.
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