math - Using javascript to decode bit values -

given following scale:

mon = 64, tue = 32, wed = 16, thu = 8, fri = 4, sat = 2, sun = 1 

how create function passed integer decode corresponding days of week?

for example, value 127 passed, how can determine days included in value?

sounds bitmask. can read bitmasks here; http://en.wikipedia.org/wiki/mask_%28computing%29

sunday 1st bit, sat 2nd, etc, mon 7th. see if day included, use binary and.

var listofdays = 127; var hassun = listofdays & 1;  var hassat = listofdays & 2; var hasfri = listofdays & 4; // etc