Week of Year2.0.0+

moment().week(Number);
moment().week(); // Number
moment().weeks(Number);
moment().weeks(); // Number

Gets or sets the week of the year.

Because different locales define week of year numbering differently, Moment.js added moment#week to get/set the localized week of the year.

The week of the year varies depending on which day is the first day of the week (Sunday, Monday, etc), and which week is the first week of the year.

For example, in the United States, Sunday is the first day of the week. The week with January 1st in it is the first week of the year.

In France, Monday is the first day of the week, and the week with January 4th is the first week of the year.

The output of moment#week will depend on the locale for that moment.

When setting the week of the year, the day of the week is retained.