// This is the main password checking function. 
function checkPassword(pwd) { 
  if(checkPasswordLength(pwd)) 
    if(checkPasswordCharsAllowed(pwd)) 
      if(checkMinPasswordChars(pwd)) return true;
  return false;
} 

// Check to make sure the password is at least minChars characters long. 
function checkPasswordLength(pw) { 
  if(pw.length<minChars) {
    alert("Your password is less than "+minChars+" characters! \nYou must choose a password that is at least "+minChars+" characters in length.") 
    return false 
  } 
  return true 
} 

// Check to make sure that all of the characters in the password are allowed. 
function checkPasswordCharsAllowed(pw) { 
  
  for(var i=0;i<pw.length;i++) {
    var ch = pw.charAt(i); 
    if((isAlpha(ch) && !lettersAllowed)) { 
      alert("Your password contains a letter!") 
      alert("Letters are not allowed in passwords.") 
      return false 
    }else if(isNumber(ch) && !numbersAllowed) { 
      alert("Your password contains a number!") 
      alert("Numbers are not allowed in passwords.") 
      return false 
    }else if(isSpecial(ch) && !specialAllowed) { 
      alert("Your password contains a special character!");
      alert("Special characters are not allowed in passwords.");
      return false;
    }else if(!isAlpha(ch) && !isNumber(ch) && !isSpecial(ch)) { 
      alert("Your password contains a non-printable character!") 
      alert("Non-printable characters are not allowed in passwords.") 
      return false 
    } 
  } 
  return true 
} 

// Check to make sure the password has the required number of alphabetic, numeric, and 
// special characters. 
function checkMinPasswordChars(pw) { 
  var alpha = 0 
  var numeric = 0 
  var special = 0 
  for(var i=0;i < pw.length;i++) {
  	var ch = pw.charAt(i);
    if(isAlpha(ch)) ++alpha 
    else if(isNumber(ch)) ++numeric 
    else if(isSpecial(ch)) ++special 
  } 
  var errMsg = "Your password does not contain the minimum number " 
  if ((minLetters >0) && (alpha < minLetters)) { 
    errMsg += "(" + minLetters + ") " 
    errMsg += "of alphabetic characters!" 
    alert(errMsg) 
    return false 
  }else if ((minNumbers >0) && (numeric < minNumbers)) { 
    errMsg += "(" + minNumbers + ") " 
    errMsg += "of numeric characters!" 
    alert(errMsg) 
    return false 
  }else if ((minSpecial >0) && (special < minSpecial)) { 
    errMsg += "(" + minSpecial + ") " 
    errMsg += "of special characters!" 
    alert(errMsg) 
    return false 
  } 
  return true 
} 

// Functions used for character identification. 
function isAlpha(ch) { 
  if(ch >= "a" && ch <= "z") return true 
  if(ch >= "A" && ch <= "Z") return true 
  return false 
} 

function isNumber(ch) { 
  if(ch >= "0" && ch <= "9") return true 
  return false 
} 

function isSpecial(ch) { 
  var special = new Array("!","\"","#","$","%","&","¡¦","(",")","*","+",",","-",".","/",":",";","<","=",">","?","@","[","\\","]","^","_","`","{","|","}","~");
  
  for (var i=0;i< special.length;i++) {
    if(ch == special[i]) return true;
  }
  return false 
} 

// Password policy 
var minChars = 8 
var lettersAllowed = true 
var numbersAllowed = true 
var specialAllowed = true 
var minLetters = 1 
var minNumbers = 1 
var minSpecial = 0