The locale to use for formatting.
Optionalformat: stringThe format pattern to use for formatting.
The duration formatter function.
The duration passed to the formatter is in milliseconds. pattern: [-][d.]hh:mm:ss[.fff] if format is constant, pattern: [-]d:hh:mm:ss.fff if format is short, pattern: [-][d:]h:mm[:ss[.FFF]] if format is long, pattern: [-][d:]hh:mm:ss[.fff] if format is racing, pattern: [-][d:][h:]mm:ss.fff
Elements in square brackets ([ and ]) are not included if they don't have values. Colons and periods are replaced with the appropriate time separator and decimal separator for the locale. Numbers are formatted using the numberFormatter function. The minus sign is replaced with the appropriate minus sign for the locale. The plus sign is replaced with the appropriate plus sign for the locale.
d: days in the time duration. h: hours in the time duration. m: minutes in the time duration. s: seconds in the time duration. f: fraction of second in the time duration (fixed). F: fraction of second in the time duration (variable trailing zeros are omitted). 'text': a quoted string is included as is. : is used to escape a characters to be included as is.
Returns a duration formatter function for the specified locale and format. The formatter function converts duration values to localized strings.