Question

Is there a helper library out there for doing these types of date calculations like in Rails?

Date.today.end_of_week

Answer 1

There is no build in function, but you could define your own:

Date.prototype.endOfWeek = function(){
  return new Date( 
      this.getFullYear(), 
      this.getMonth(), 
      this.getDate() + 6 - this.getDay() 
  );
};

var now = new Date();

// returns next saturday; and returns saturday if it is saturday today.
console.log( now.endOfWeek() );