Não funcionou | jQuery: avance na biblioteca mais popular do mercado parte 2

<!DOCTYPE html>
<html lang="pt-br">
<head>
    <meta charset="UTF-8">
    <title>Alura Typer</title>
    <link rel="stylesheet" href="css/libs/materialize.min.css">
    <link rel="stylesheet" href="css/libs/google-fonts.css">
    <link rel="stylesheet" href="css/estilos.css">
</head>
<body>
    <div class="container">
        <h1 class="center">Alura Typer</h1>
        <p class="frase center">Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.</p>

        <ul class="informacoes center">
            <li>
                <i class="small material-icons icones">description</i>
                <span id="tamanho-frase">5</span> palavras
            </li>
            <li>
                <i class="small material-icons icones">query_builder</i>
                <span id="tempo-digitacao">10</span> segundos
            </li>
        </ul>

        <textarea class="campo-digitacao" rows="8" cols ="40"></textarea>

        <div class="botoes">
            <a id="botao-reiniciar" class="btn-floating btn-large waves-effect waves-light red">
                <i class="material-icons">restore</i>
            </a>
            <a id="botao-placar" class="btn-floating btn-large waves-effect waves-light green">
                <i class="material-icons">assignment</i>
            </a>
            <a id="botao-frase" class="btn-floating btn-large waves-effect waves-light blue">
                <i class="material-icons">shuffle</i>
            </a>
        </div>

        <ul class="center">
            <li><span id="contador-caracteres">0</span> caracteres</li>
            <li><span id="contador-palavras">0</span> palavras</li>
        </ul>

        <section class="placar">
            <h3 class="center">Placar</h3>
            <table class="centered bordered">
                <thead>
                    <tr>
                        <th>Nome</th>
                        <th>No. de palavras</th>
                        <th>Remover</th>
                    </tr>
                </thead>
                <tbody>

                </tbody>
            </table>
        </section>
    </div>

    <script src="js/jquery.js"></script>
    <script src="js/materialize.min.js"></script>
    <script src="js/main.js"></script>
    <script src="js/placar.js"></script>
    <script src="js/frase.js"></script>

</body>
</html>

$("#botao-frase").click(fraseAleatoria);

function fraseAleatoria() {
    $.get("http://localhost:3000/frases", trocaFraseAleatoria);
}

function trocaFraseAleatoria(data) {
    var frase = $(".frase");
    var numeroAleatorio = Math.floor(Math.random() * data.length);

    frase.text(data[numeroAleatorio].texto);
}

estou com esse erro no console quando clico no botão para mudar a frase e a frase não muda, eu baixei o arquivo zip e fiz as mudanças conforme a aula.

principal.html:1 XMLHttpRequest cannot load http://localhost:3000/frases. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access.