script.js

var chars = [" ", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "1", "2", "3", "4", "5", "6", "7", "8", "9", "0", ",", ".", "!", "?", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"]

function main() {
    if(document.title != "Main Menu") {
        if (document.title != "Hacker") {
            if (document.getElementById("shift").value == "") {
                document.getElementById("shift").value = "1";
            }

            while (document.getElementById("shift").value > chars.length) {
                document.getElementById("shift").value = document.getElementById("shift").value - chars.length;
            }

            shift = Number(document.getElementById("shift").value);

        }

        var message = document.getElementById("message").value;

        var splitMessage = message.split("");

        var shiftedIndex;

        if (document.title == "Encryptor") {
            var encryptedMessage = [];

            for (var i = 0; i < splitMessage.length; i++) {
                if (chars.indexOf(splitMessage[i]) != "-1") {
                    shiftedIndex = chars.indexOf(splitMessage[i]) + shift;
                    while (shiftedIndex >= chars.length) {
                        shiftedIndex = shiftedIndex - chars.length;
                    }
                    while (shiftedIndex < 0) {
                        shiftedIndex = shiftedIndex + chars.length;
                    }
                    encryptedMessage.push(chars[shiftedIndex]);
                }
            }
        
            document.getElementById("encryptedMessage").value = encryptedMessage.join("");

        } else if (document.title == "Decryptor") {
            var decryptedMessage = [];

            for (var i = 0; i < splitMessage.length; i++) {
                if (chars.indexOf(splitMessage[i]) != "-1") {
                    shiftedIndex = chars.indexOf(splitMessage[i]) - shift;
                    while (shiftedIndex >= chars.length) {
                        shiftedIndex = shiftedIndex - chars.length;
                    }
                    while (shiftedIndex < 0) {
                        shiftedIndex = shiftedIndex + chars.length;
                    }
                    decryptedMessage.push(chars[shiftedIndex]);
                }
            }

            document.getElementById("decryptedMessage").value = decryptedMessage.join("");
        } else if (document.title == "Hacker") {

            var decryptedMessages = [];
            for (var shift = 0; shift < chars.length; shift++) {
                var decryptedMessage = [];

                for (var i = 0; i < splitMessage.length; i++) {
                    if (chars.indexOf(splitMessage[i]) != "-1") {
                        shiftedIndex = chars.indexOf(splitMessage[i]) + shift;
                        while (shiftedIndex >= chars.length) {
                            shiftedIndex = shiftedIndex - chars.length;
                        }
                        while (shiftedIndex < 0) {
                            shiftedIndex = shiftedIndex + chars.length;
                        }
                        decryptedMessage.push(chars[shiftedIndex]);
                    }
                }

                if (decryptedMessage != []) {
                    console.log(decryptedMessage.join(""));
                    if (decryptedMessage.join("").includes(document.getElementById("word").value)) {
                    decryptedMessages.push(decryptedMessage.join(""));
                    }
                }
            }
            document.getElementById("decryptedMessage").value = decryptedMessages.join("\n");
        }
    }
}

var loop = setInterval(main, 100);