JavaScript関数を再度実行した後、テキスト領域をクリアするのに助けが必要

「パスワードの生成」ボタンがクリックされたときにのみポップアップを表示するには、writePassword関数にすべてのポップアップを挿入する必要があります。

   function writePassword() {
        
        // Request length of the password
        plength = parseInt(prompt("Welcome to Password Generator 2020. To begin, please enter a length of your password from 8-128.", ""));
    
        // Require number
        while (isNaN(plength)) {
            plength = parseInt(prompt("This is not a number. Please enter a number between 8 - 128.", ""));
        }
    
        // Require length    
        while (plength < 8 || plength > 128) {
            plength = parseInt(prompt("Enter length of password.* Length must be between 8 - 128 characters", ""));
        }
    
        // Confirm lower case letters 
        selectLowerCase = confirm("Use lower case letters?");
        // Confirm upper case letters
        selectUpperCase = confirm("Use upper case letters?");
        //Confirm numeric characters 
        selectNumber = confirm("Use numbers?");
        //Confirm special characters
        selectSpecial = confirm("Use special characters?");
    
        var password = generatePassword();
        document.querySelector("#password").value = password;
        
    }

次に、パスワード領域をクリアするにはuserPassword、新しいパスワードの生成を開始する前に、変数をnull文字列に設定する必要があります（ランダムに生成された文字を追加するため）。

function generatePassword() {
    userPassword = "";
    if (selectLowerCase) {
        passwordGroup += lowerCase;
    }
    if (selectUpperCase) {
        passwordGroup += upperCase;
    }
    if (selectNumber) {
        passwordGroup += numbers;
    }
    if (selectSpecial) {
        passwordGroup += specialCharacter;
    }
    for (let i = 0; i < plength; i++) {
        userPassword += passwordGroup.charAt(
            Math.floor(Math.random() * passwordGroup.length)
        );
    }
    return userPassword;
}

これは完全なJavaScriptコードです。

   // GenerateBtn
    var generateBtn = document.querySelector("#generate");
    
    // Define variables
    var selectLowerCase;
    var selectUpperCase;
    var selectNumber;
    var selectSpecial;
    
    // Set variables  
    var plength = 0;
    var lowerCase = "abcdefghijklmnopqrstuvwxyz";
    // Uppercase conversion
    var upperCase = lowerCase.toUpperCase();
    var numbers = "1234567890";
    var specialCharacter = "!#$%&'()*+,-./:;?@][^_`{|}~'<=>";
    var userPassword = "";
    var passwordGroup = "";
    var plength;
    var selectLowerCase;
    var selectUpperCase;
    var selectNumber;
    var selectSpecial;
    
    // Function writes password to the #password input
    function writePassword() {
        
        // Request length of the password
        plength = parseInt(prompt("Welcome to Password Generator 2020. To begin, please enter a length of your password from 8-128.", ""));
    
        // Require number
        while (isNaN(plength)) {
            plength = parseInt(prompt("This is not a number. Please enter a number between 8 - 128.", ""));
        }
    
        // Require length    
        while (plength < 8 || plength > 128) {
            plength = parseInt(prompt("Enter length of password.* Length must be between 8 - 128 characters", ""));
        }
    
        // Confirm lower case letters 
        selectLowerCase = confirm("Use lower case letters?");
        // Confirm upper case letters
        selectUpperCase = confirm("Use upper case letters?");
        //Confirm numeric characters 
        selectNumber = confirm("Use numbers?");
        //Confirm special characters
        selectSpecial = confirm("Use special characters?");
    
        var password = generatePassword();
        document.querySelector("#password").value = password;
        
    }
    
    // Clicking btn runs funtion
    generate.addEventListener("click", writePassword);
    
    
    // Call function to generate password 
    generatePassword();
    
    // Write generated password on page
    document.getElementById("password").innerHTML = userPassword;
    
    // From selected options randomly generate password.
    function generatePassword() {
        userPassword = "";
        if (selectLowerCase) {
            passwordGroup += lowerCase;
        }
        if (selectUpperCase) {
            passwordGroup += upperCase;
        }
        if (selectNumber) {
            passwordGroup += numbers;
        }
        if (selectSpecial) {
            passwordGroup += specialCharacter;
        }
        for (let i = 0; i < plength; i++) {
            userPassword += passwordGroup.charAt(
                Math.floor(Math.random() * passwordGroup.length)
            );
        }
        return userPassword;
    }
    
    /* || COPY FUNCTION || */
    
    // https://www.w3schools.com/howto/howto_js_copy_clipboard.asp
    var copy = document.querySelector("#copy");
    copy.addEventListener("click", function() {
        copyPassword();
    });
    
    function copyPassword() {
        document.getElementById("password").select();
        document.execCommand("Copy");
        alert("Password copied to clipboard!");
    }