node.js - counter not running inside coffeescript createInterface function -

i want make function "countryipcounterstream" read large text file lines in format: 100575232 100577279 5.254.168.0 - 5.254.175.255 se - , calculate sum of absolute difference between numbers in 1st , 2nd column 4th column code == countrycode given function argument.

problem in line: if line[3] == countrycode counter= +line[1]-+line[0] clause counter= +line[1]-+line[0] after "then" won't work! however, noticed if replace else, replaced part after "then" runs perfectly. example console.log line[x].

code followed:

exports.countryipcounterstream = (countrycode, cb) ->   return cb() unless countrycode   heapusagebefore = process.memoryusage().heapused   console.log "program init normally, "   instream = fs.createreadstream "#{__dirname}/../data/geo.txt", 'utf8'   console.log "streaming started"   line_counter = 0   outstream = new stream   instream.on('data', (chunk) ->     console.log chunk.length     in [0...chunk.length-1] 1       if chunk[i] == 10 line_counter += 1     )   console.log 'line_counter', line_counter   rl = readline.createinterface(instream, outstream)   console.log 'country:', countrycode   counter = 0   rl.on('line', (line) ->     line = line.split '\t'     counter += 1     if line[3] == countrycode counter= +line[1]-+line[0]     )   rl.close()   console.log "finishing up, counter = ", counter   heapusageafter = process.memoryusage().heapused   heapusageincrease = heapusageafter / heapusagebefore   console.log heapusageincrease.tofixed(2)   cb null, counter