[Bug]: CJS `SyntaxError: Identifier 'zod' Has Already Been Declared`

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Bug Fix: CJS SyntaxError: Identifier 'zod' has already been declared

In this article, we will be discussing a bug that occurs when using the zod library in a CommonJS (CJS) environment. The bug results in a SyntaxError: Identifier 'zod' has already been declared error. We will explore the reproduction steps, expected behavior, and actual behavior, and then dive into the solution to fix this issue.

To reproduce this bug, follow these steps:

  1. Clone the repository from the given link: https://stackblitz.com/edit/github-pcx6nmxb?file=src%2Fentry.js
  2. Run the command pnpm build && node dist/entry.js in your terminal.

No errors should be thrown when running the command pnpm build && node dist/entry.js.

However, when running the command pnpm build && node dist/entry.js, the following error is thrown:

SyntaxError: Identifier 'zod' has already been declared (32:4)
    at compileSourceTextModule (https://vbwimvyraagithub-o4eu.w-credentialless-staticblitz.com/builtins.97a3df4f.js:164:3415)
    at ModuleLoader.moduleStrategy (https://vbwimvyraagithub-o4eu.w-credentialless-staticblitz.com/builtins.97a3df4f.js:163:2752)
    at #a (https://vbwimvyraagithub-o4eu.w-credentialless-staticblitz.com/builtins.97a3df4f.js:157:4044)
    at ModuleLoader.loadAndTranslate (https://vbwimvyraagithub-o4eu.w-credentialless-staticblitz.com/builtins.97a3df4f.js:157:4594)
    at async ModuleJob._link (https://vbwimvyraagithub-o4eu.w-credentialless-staticblitz.com/builtins.97a3df4f.js:158:1406)

The system info for this bug is as follows:

StackBlitz

This issue has been reported on the GitHub repository for tsdown at https://github.com/rolldown/tsdown/issues/196.

To fix this issue, we need to ensure that the zod library is not being imported twice in our code. We can do this by removing any unnecessary imports of zod and making sure that we are only importing it once in our code.

Here is an example of how we can fix this issue:

// Remove any unnecessary imports of zod
// import { zod } from 'zod';

// Import zod only once
import { zod } from 'zod';

// Use zod in our code
const schema = zod.object({
  name: zod.string(),
  age: zod.number(),
});

// Test the schema
const result = schema.parse({ name: 'John Doe', age: 30 });
console.log(result);

By following these steps, we can fix the SyntaxError: Identifier 'zod' has already been declared error and ensure that our code runs without any issues.

In this article, we discussed a bug that occurs when using the zod library in a CommonJS (CJS) environment. We explored the reproduction steps, expected behavior, and actual behavior, and then dove into the solution to fix this issue. By removing any unnecessary imports of zod and making sure that we are only importing it once in our code, we can fix the SyntaxError: Identifier 'zod' has already been declared error and ensure that our code runs without any issues.

Here are some troubleshooting tips that can help you fix this issue:

  • Make sure that you are only importing zod once in your code.
  • Remove any unnecessary imports of zod.
  • Check your code for any duplicate imports of zod.
  • Use a linter or code formatter to help you catch any duplicate imports of zod.

By following these troubleshooting tips, you can help fix the SyntaxError: Identifier 'zod' has already been declared error and ensure that your code runs without any issues.
Q&A: Bug Fix - CJS SyntaxError: Identifier 'zod' has already been declared

In our previous article, we discussed a bug that occurs when using the zod library in a CommonJS (CJS) environment. The bug results in a SyntaxError: Identifier 'zod' has already been declared error. We explored the reproduction steps, expected behavior, and actual behavior, and then dove into the solution to fix this issue.

In this article, we will be answering some frequently asked questions (FAQs) related to this bug. We will cover topics such as the cause of the bug, how to reproduce it, and how to fix it.

A: The cause of the SyntaxError: Identifier 'zod' has already been declared error is due to the fact that the zod library is being imported twice in the code. This can happen when there are duplicate imports of zod in the code, or when zod is being imported in a way that creates a duplicate identifier.

A: To reproduce this bug, you can follow these steps:

  1. Clone the repository from the given link: https://stackblitz.com/edit/github-pcx6nmxb?file=src%2Fentry.js
  2. Run the command pnpm build && node dist/entry.js in your terminal.

A: The expected behavior when running the command pnpm build && node dist/entry.js is that no errors should be thrown.

A: The actual behavior when running the command pnpm build && node dist/entry.js is that a SyntaxError: Identifier 'zod' has already been declared error is thrown.

A: To fix this bug, you need to ensure that the zod library is not being imported twice in your code. You can do this by removing any unnecessary imports of zod and making sure that you are only importing it once in your code.

Here is an example of how you can fix this issue:

// Remove any unnecessary imports of zod
// import { zod } from 'zod';

// Import zod only once
import { zod } from 'zod';

// Use zod in your code
const schema = zod.object({
  name: zod.string(),
  age: zod.number(),
});

// Test the schema
const result = schema.parse({ name: 'John Doe', age: 30 });
console.log(result);

A: Here are some troubleshooting tips that can help you fix this issue:

  • Make sure that you are only importing zod once in your code.
  • Remove any unnecessary imports of od.
  • Check your code for any duplicate imports of zod.
  • Use a linter or code formatter to help you catch any duplicate imports of zod.

By following these troubleshooting tips, you can help fix the SyntaxError: Identifier 'zod' has already been declared error and ensure that your code runs without any issues.

In this article, we answered some frequently asked questions (FAQs) related to the SyntaxError: Identifier 'zod' has already been declared error. We covered topics such as the cause of the bug, how to reproduce it, and how to fix it. By following the troubleshooting tips and solution provided in this article, you can help fix this issue and ensure that your code runs without any errors.