d3.timeFormatDefaultLocale()

d3.timeFormatDefaultLocale(definition)

Equivalent to d3.timeFormatLocale, except it also redefines d3.timeFormat, d3.timeParse, d3.utcFormat and d3.utcParse to the new locale’s locale.format, locale.parse, locale.utcFormat and locale.utcParse. If you do not set a default locale, it defaults to U.S. English.