Server-Side Locale Management: Resolving 'window is not defined' in ESHOPMAN Storefront SDK

As an e-commerce platform built on Node.js/TypeScript, ESHOPMAN empowers merchants to deploy high-performance storefronts directly through HubSpot CMS. A key component for developers interacting with the ESHOPMAN Store API and managing storefront data is the ESHOPMAN Storefront SDK. This SDK is designed to work seamlessly across various environments, including both client-side browsers and server-side rendering (SSR) contexts.

Recently, a critical issue was identified concerning the setLocale() method within the ESHOPMAN Storefront SDK when used in a Node.js server environment, such as during server-side rendering for HubSpot CMS storefronts.

The Challenge: ReferenceError: window is not defined During Server-Side Locale Setting

Developers using the ESHOPMAN Storefront SDK in a Node.js environment, common for server-rendered ESHOPMAN storefronts on HubSpot CMS, encountered an unexpected error when attempting to set the locale using Client.setLocale(). Instead of gracefully handling the server context by logging a warning and returning, the method threw a ReferenceError: window is not defined.

This issue stemmed from a specific implementation detail within the SDK's setLocale() method. The code snippet below illustrates the problematic check:

setLocale(locale: string) {
  if (!window) {
    this.logger.warn("setLocale is not available in the server environment. ...")
    return
  }
  // ... further logic
}

In a Node.js environment, the global window object simply does not exist. Directly referencing window in the conditional check if (!window) causes a ReferenceError to be thrown before the intended warning message could be logged. This effectively halted the server-side rendering process, preventing proper locale initialization and potentially impacting the user experience for ESHOPMAN storefronts.

Expected Behavior vs. Actual Outcome

The design intent for setLocale() was to detect a non-browser environment, log a warning indicating its unavailability on the server, and then exit gracefully. However, the actual behavior was an abrupt crash due to the ReferenceError.

The ESHOPMAN Solution: Safe Environment Checks

The resolution to this issue lies in adopting a more robust and universally compatible method for checking the presence of the browser's window object. Instead of directly evaluating !window, the standard and safest practice in universal JavaScript — code intended to run both client-side and server-side — is to use typeof window === "undefined".

This approach checks the type of the window variable. If window is not defined, typeof window will return the string "undefined", allowing the condition to be met without throwing an error. Notably, other helper functions within the ESHOPMAN Storefront SDK, such as hasStorage and getBaseUrl, already correctly implement this safe check.

The ESHOPMAN team has addressed this bug, and a fix has been implemented to ensure that setLocale() now correctly logs a warning and returns when called in a server-side Node.js environment, aligning with the expected behavior. This improvement enhances the stability and predictability of ESHOPMAN storefronts during server-side rendering on HubSpot CMS.

Key Takeaway for ESHOPMAN Developers

For ESHOPMAN developers working with server-side rendering and the ESHOPMAN Storefront SDK, this insight reinforces the importance of using robust environment checks. When writing universal JavaScript code that might execute in both browser and Node.js contexts, always prefer typeof window === "undefined" to safely determine the execution environment. This practice ensures your ESHOPMAN storefronts remain resilient and performant, whether rendered client-side or server-side via HubSpot CMS.