Does this respect the user's locale for number formatting?

Yes, pretty-bytes does respect the user's locale for number formatting. The library provides a locale option that controls how numbers are formatted according to different localization standards.

The locale option works in three ways [README]:

1. false (default): Output won't be localized
2. true: Localizes using the system/browser locale
3. string or string[]: Uses a specific BCP 47 language tag (e.g., 'de', 'en')

The actual localization is handled by the toLocaleString function [index.js:L55-L65], which delegates to JavaScript's native Number.toLocaleString() method. When a locale is specified as a string or array, it's passed directly to this method:

if (typeof locale === 'string' || Array.isArray(locale)) {
    result = number.toLocaleString(locale, options);
}

For example, the test suite demonstrates locale-specific formatting [test.js:L71-L110]:

• German ('de') uses comma as decimal separator and periods for thousands: '1,34 kB' → '1.000.000 YB'
• English ('en') uses period as decimal separator and commas for thousands: '1.34 kB' → '1,000,000 YB'

FOLLOW_UPS:

• How does fixedWidth padding affect locale formatting?
• What happens with minimumFractionDigits and locale options?
• Can you combine locale with bits and binary options?