Why does the Square Node.js SDK throw 'Client is not a constructor'?

Below is an explanation of what might be causing the issue:

Likely Cause: Version Mismatch

The error

TypeError: Client is not a constructor

usually indicates that the imported Client isn’t actually a class (or constructor) in the version of the package you’re using. In other words, the code you're using (and shown in Square’s developer site) is for a newer version of the Square Node.js SDK. If your project has an older version installed, then the API you’re trying to use might not exist, or the way to initialize the client is different.

What to Check and Do

1. Verify Package Version:
   Ensure that you have the latest version of the Square SDK installed. You can check your package.json or run:

   BASHCopied
   npm list square

   If you’re not on the version that supports the new Client (usually the one referenced on the developer site), update it:

   BASHCopied
   npm install square@latest

2. Review the Import Statement:
   The instructions indicate that you should import both Client and Environment from the package, like so:

   JAVASCRIPTCopied
   const { Client, Environment } = require('square');

   If your installed version doesn’t export a Client constructor, this import will not work as expected.

3. Environment Variables:
   While not directly responsible for the "not a constructor" error, ensure that your environment variables (SQUARE_ENVIRONMENT and SQUARE_ACCESS_TOKEN) are set correctly. Keep in mind that if you’re trying to dynamically set the environment based on the variable (instead of hardcoding Environment.Sandbox), you might need logic like:

   JAVASCRIPTCopied
   const env = process.env.SQUARE_ENVIRONMENT === 'production'
     ? Environment.Production
     : Environment.Sandbox;
   
   const client = new Client({
       bearerAuthCredentials: {
           accessToken: process.env.SQUARE_ACCESS_TOKEN
       },
       environment: env
   });

   However, the "not a constructor" error is unlikely to stem from this part of your code unless somehow an unexpected value is interfering with the import.

Summary

• The error is most likely due to using an older version of the Square package that does not export Client as a constructor.
• Updating the package to the version that matches Square Developer’s documentation should resolve the issue.
• Double-check your environment variable usage to ensure correct runtime values.

By confirming that you’re using the correct and up-to-date Square SDK, you should be able to initialize your client (and eventually create a customer) without encountering the "TypeError: Client is not a constructor" error.