如何强制表单仅通过Google搜索在特定站点内进行搜索

<form id="searchForm">
  <input type="text" id="searchInput" placeholder="在特定站点内搜索">
  <button type="submit">搜索</button>
</form>

<script>
  document.getElementById("searchForm").addEventListener("submit", function(event) {
    event.preventDefault(); // 阻止表单默认提交行为

    var searchKeyword = document.getElementById("searchInput").value;
    var searchUrl = "https://www.google.com/search?q=site:特定站点URL " + searchKeyword;

    window.location.href = searchUrl;
  });
</script>