- /** Determine if the current device is from mainland China using Emojis
    - * If the *Taiwan flag* characters cannot be displayed in color (rendered as black and white letters or not rendered at all), it indicates a device more likely to be from mainland China.
    - * To avoid false positives, *smiley face* will be used as a comparison:
    - * If the device cannot even render regular Emojis in color (such as Linux without colored Emoji fonts,
    - * a browser with fingerprint protection enabled), it returns null to indicate that it cannot determine the source, rather than falsely reporting true. */