Can you simplify this Regular Expression? Must be JavaScript compatible.

gistfile1.txt

/(MONDAY|TUESDAY|WEDNESDAY|THURSDAY|FRIDAY|SATURDAY|SUNDAY)(\-(MONDAY|TUESDAY|WEDNESDAY|THURSDAY|FRIDAY|SATURDAY|SUNDAY)|( AND (MONDAY|TUESDAY|WEDNESDAY|THURSDAY|FRIDAY|SATURDAY|SUNDAY)))? \/ (1AM|2AM|3AM|4AM|5AM|6AM|7AM|8AM|9AM|10AM|11AM|MIDDAY|1PM|2PM|3PM|4PM|5PM|6PM|7PM|8PM|9PM|10PM|11PM|MIDNIGHT)\-(1AM|2AM|3AM|4AM|5AM|6AM|7AM|8AM|9AM|10AM|11AM|MIDDAY|1PM|2PM|3PM|4PM|5PM|6PM|7PM|8PM|9PM|10PM|11PM|MIDNIGHT) \/ (WEEKLY|BI-WEEKLY|MONTHLY|BI-MONTHLY)/

Samples

MONDAY / 9AM-10PM / WEEKLY
MONDAY-THURSDAY / 9AM-10PM / WEEKLY
TUESDAY AND THURSDAY / 9AM-10PM / WEEKLY
MONDAY / 9AM-MIDDAY / BI-WEEKLY
MONDAY-THURSDAY / 11PM-MIDNIGHT / MONTHLY
TUESDAY AND THURSDAY / MIDDAY-3PM / BI-MONTHLY
THURSDAY / MIDNIGHT-2AM / MONTHLY

@miksago not really, but this may help http://regex101.com/r/mL8iA4/1

If by "simplify" you meant ⛳
/(MON|TUES|WEDNES|THURS|FRI|SATUR|SUN)DAY(\-(MON|TUES|WEDNES|THURS|FRI|SATUR|SUN)DAY|( AND (MON|TUES|WEDNES|THURS|FRI|SATUR|SUN)DAY))? \/ ((([1-9]|1[01])[AP]M)|MID(NIGHT|DAY)?)\-((([1-9]|1[01])[AP]M)|MID(NIGHT|DAY)?) \/ ((BI-)?(WEEK|MONTH)LY)/

This one lets you capture the separator between the two days and doesn't repeat the days 3 times:

((?:MON|TUES|WEDNES|THURS|FRI|SATUR|SUN)DAY)(-((?:MON|TUES|WEDNES|THURS|FRI|SATUR|SUN)DAY)| AND ((?:MON|TUES|WEDNES|THURS|FRI|SATUR|SUN)DAY))? \/ ((?:[1-9]|1[01])[AP]M|MID(?:DAY|NIGHT))-((?:[1-9]|1[01])[AP]M|MID(?:DAY|NIGHT)) \/ ((?:BI-)?(?:WEEKLY|MONTHLY))

Created and tested with:

var samples = [
  'MONDAY / 9AM-10PM / WEEKLY'
, 'MONDAY-THURSDAY / 9AM-10PM / WEEKLY'
, 'TUESDAY AND THURSDAY / 9AM-10PM / WEEKLY'
, 'MONDAY / 9AM-MIDDAY / BI-WEEKLY'
, 'MONDAY-THURSDAY / 11PM-MIDNIGHT / MONTHLY'
, 'TUESDAY AND THURSDAY / MIDDAY-3PM / BI-MONTHLY'
, 'THURSDAY / MIDNIGHT-2AM / MONTHLY'
]

var parts = {
  day: '((?:MON|TUES|WEDNES|THURS|FRI|SATUR|SUN)DAY)'
, time: '((?:[1-9]|1[01])[AP]M|MID(?:DAY|NIGHT))'
, recur: '((?:BI-)?(?:WEEKLY|MONTHLY))'
}
var template = '^{day}(?:(-| AND ){day})? / {time}-{time} / {recur}$'
var re = new RegExp(template.replace(/{(\w+)}/g, function(match, part) { return parts[part] }))

console.log('Testing: /' + re.source + '/')

samples.forEach(function(input) {
  console.log(input + ': ' + re.test(input))
})

var fields = ['day1', 'rangeType', 'day2', 'from', 'to', 'recurrence']

function parse(input) {
  var match = re.exec(input)
  if (!match) { return null }
  var obj = {}
  for (var i = 0; i < fields.length; i++) {
    obj[fields[i]] = match[i + 1] || null
  }
  return obj
}

samples.forEach(function(input) {
  console.log(JSON.stringify(parse(input)))
})

Logged output:

{"day1":"MONDAY","rangeType":null,"day2":null,"from":"9AM","to":"10PM","recurrence":"WEEKLY"}
{"day1":"MONDAY","rangeType":"-","day2":"THURSDAY","from":"9AM","to":"10PM","recurrence":"WEEKLY"}
{"day1":"TUESDAY","rangeType":" AND ","day2":"THURSDAY","from":"9AM","to":"10PM","recurrence":"WEEKLY"}
{"day1":"MONDAY","rangeType":null,"day2":null,"from":"9AM","to":"MIDDAY","recurrence":"BI-WEEKLY"}
{"day1":"MONDAY","rangeType":"-","day2":"THURSDAY","from":"11PM","to":"MIDNIGHT","recurrence":"MONTHLY"}
{"day1":"TUESDAY","rangeType":" AND ","day2":"THURSDAY","from":"MIDDAY","to":"3PM","recurrence":"BI-MONTHLY"}
{"day1":"THURSDAY","rangeType":null,"day2":null,"from":"MIDNIGHT","to":"2AM","recurrence":"MONTHLY"}

Looks readable to me. What problem are you trying to solve?

@jasiek it's just to valid some input for Radio Show scheduling. Doesn't need to be anything fancy for now.