Untitled

<!DOCTYPE html>
        <html>
          <head>
              <script>
                 document.getElementById("btnSearch")
                         .addEventListener("click",showAlert);
              function showAlert() {
                alert("hello world");
              }
              </script>
          </head>
          <body>
            <div>
              <label>Enter code</label>
              <input type="text" id="txtStudentID"/>
              <button id="btnSearch">Search</button>
            </div>
          </body>
        </html>

function doGet() {
  return HtmlService.createHtmlOutputFromFile('Index');
}

<input type="button" value="Search"
      onclick="google.script.run
          .withSuccessHandler(showAlert)
          .withUserObject(this)" />