DefinePlugin limitations for runtime time zone configuration

When using webpack.DefinePlugin to inject environment variables, there is a distinction between build-time constant replacement and runtime environment behavior. A common goal is to ensure that date and time formatting remains consistent across different regional deployments.

Because DefinePlugin performs a direct textual replacement during the bundling process, any injected time zone identifier (such as a TZ variable) becomes a hard-coded string within the emitted bundle. This occurs regardless of the target configuration used for the build.

Since browser-based Intl and Date objects resolve time zones based on the host system's local settings, a build-time constant cannot override the user's regional environment at runtime.

• Does DefinePlugin provide any mechanism to influence the runtime behavior of the browser's native Intl.DateTimeFormat?
• What are the constraints of using build-time constants to manage regional date conversions compared to runtime polyfills?