Returning password based on user input - passwords

Question

Trainee Web Developer here! I have created a password generator for a homework challenge - user can select password length and whether password contains numbers, special characters, upper or lower cased characters. I can generate a password but although user can select these options, the generated password doesn't always contain what they want or don't want.
I think that I may need to specify something else in the if statement but although I've played around with it, I can't see what I'm missing. I'd appreciate any pointers in the right direction please :)
// Get references to the #generate element
var generateBtn = document.querySelector('#generate');
// Write password to the #password input
function writePassword() {
var password = generatePassword();
var passwordText = document.querySelector('#password');
passwordText.value = password;
};
// Add event listener to generate button
generateBtn.addEventListener('click', writePassword);
// Array of special characters to be included in password
var specialCharacters = ["!\"#$%&'()*+,-./:;<=>?#[\]^_`{|}~"];
// Array of numeric characters to be included in password
var numericCharacters = ["0123456789"];
// Array of lowercase characters to be included in password
var lowerCasedCharacters = ["abcdefghijklmnopqrstuvwxyz"];
// // Array of uppercase characters to be included in password
var upperCasedCharacters = ["ABCDEFGHIJKLMNOPQRSTUVWXYZ"];
var chosenChars = "";
//Function that will eventually return the generated password
function generatePassword() {
var result = "";
//Prompt user for password length
var userChoice = prompt("How many characters would you like your password to contain (10-64)?");
if (userChoice < 10 || userChoice > 64) {
alert("Your password must contain between 10 and 64 characters. Please try again.")
return generatePassword()
}
//Prompt user for password options
var lower = confirm("Click OK to confirm if you would like to include lowercase letters.");
var upper = confirm("Click OK to confirm if you would like to include uppercase letters.");
var numChar = confirm("Click OK to confirm if you would like to include numeric characters.");
var specChar = confirm("Click OK to confirm if you would like to include special characters.");
//Prompts user to ensure they choose at least one character type
if(!lower && !upper && !numChar && !specChar) {
alert("Please choose at least one character type.")
return generatePassword()
}
//When user clicks ok, their choice will be saved in chosenChars variable
if (lower === true) {
chosenChars += lowerCasedCharacters
}
if (upper === true) {
chosenChars += upperCasedCharacters
}
if (numChar === true) {
chosenChars += numericCharacters
}
if (specChar === true) {
chosenChars += specialCharacters
}
//Takes result from chosenChars and selects at random based on user's choice of length
for (var i = 0; i < userChoice; i++) {
result +=chosenChars.charAt(Math.floor(Math.random() * chosenChars.length));
}
return result;
}
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