Encode and Decode Message

function solve () {
    let textAreas = Array.from(document.getElementsByTagName('textarea')); // 0 === sent message , 1 === received message
    let buttons = Array.from(document.getElementsByTagName('button'));     // 0 === sent message , 1 === received message

    buttons[0].addEventListener('click', encodeAndSend);
    buttons[1].addEventListener('click', decodeAndRead);

    function encodeAndSend() {
        let sentMessage = textAreas[0].value.split('');
        let encodedMessage = [];

        sentMessage.forEach(c => {
            let ascii = c.charCodeAt(0) + 1;
            encodedMessage.push(String.fromCharCode(ascii));
        });

        textAreas[1].value = encodedMessage.join("");
        textAreas[0].value = "";
    }

    function decodeAndRead() {

        let receivedMsg = textAreas[1].value.split('');
        let decodedMsg = [];

        receivedMsg.forEach(c => {
            let ascii = c.charCodeAt(0) - 1;
            decodedMsg.push(String.fromCharCode(ascii));
        });

        textAreas[1].value = decodedMsg.join("");
    }
}