test.js

document.writeln("虾米大王，从0到1教程"+"<br>");

t326.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../../js/jquery-3.5.1.js"></script>
    <script>
        //$.getScript()方法
        $(function () {
           $("#btn1").click(function () {
               $.getScript("test.js");
           });
        });
    </script>
</head>
<body>
    <input type="button" id="btn1" value="加载">
</body>
</html>