index.js

const { hash } = window.location;

const message = atob(hash.replace("#", ""));

if (message) {
    document.querySelector("#message-form").classList.add("hide");
    document.querySelector("#message-show").classList.remove("hide");
    document.querySelector("h1").innerHTML = message;
}

document.querySelector("form").addEventListener("submit", (event) => {
    event.preventDefault();

    document.querySelector("#message-form").classList.add("hide");
    document.querySelector("#link-form").classList.remove("hide");
    const input = document.querySelector("#message-input");
    const encrypted = btoa(input.value);
    const linkInput = document.querySelector("#link-input");
    linkInput.value = `${window.location}#${encrypted}`;
    linkInput.select();
});