Jquery File Extension Validation

gistfile1.coffee

validVideoFileExtensions = [ ".mp4", ".m4v", ".mov" ]
validAudioFileExtensions = [ ".mp3", ".m4a" ]

$("input#sermon_video").live "change", ->
  if this.type is "file"
    sFileName = this.value
    if sFileName.length > 0
      blnValid = false
      j = 0

      while j < validVideoFileExtensions.length
        sCurExtension = validVideoFileExtensions[j]
        if sFileName.substr(sFileName.length - sCurExtension.length, sCurExtension.length).toLowerCase() is sCurExtension.toLowerCase()
          blnValid = true
          $("input[type=submit]").removeAttr("disabled");
          break
        j++
      unless blnValid
        $("input[type=submit]").attr("disabled", "disabled");
        alert "Sorry, " + sFileName + " is invalid, allowed extensions are: " + validVideoFileExtensions.join(", ")
        return false
        
$("input#sermon_audio").live "change", ->
  if this.type is "file"
    sFileName = this.value
    if sFileName.length > 0
      blnValid = false
      j = 0

      while j < validAudioFileExtensions.length
        sCurExtension = validAudioFileExtensions[j]
        if sFileName.substr(sFileName.length - sCurExtension.length, sCurExtension.length).toLowerCase() is sCurExtension.toLowerCase()
          blnValid = true
          $("input[type=submit]").removeAttr("disabled");
          break
        j++
      unless blnValid
        $("input[type=submit]").attr("disabled", "disabled");
        alert "Sorry, " + sFileName + " is invalid, allowed extensions are: " + validAudioFileExtensions.join(", ")
        return false