Write a javascript function called isDayName that takes a string parameter and returns true if the string passed in is a day of the week.

Here is the function in action: assert.equal(isDayName('Saturday'), true); assert.equal(isDayName('Monday'), true); assert.equal(isDayName('January'), false);

These asserts will test your function:

assert.equal(isDayName('Saturday'), true); assert.equal(isDayName('Monday'), true); assert.equal(isDayName('January'), false, 'January is not a day');