PHP下拉菜单列表类别

我希望当我选择书籍时，下面的类别，如产品[菜单、名称、出版商等]只会在我选择书籍时显示，我不希望电影、音乐等的类别相同。。请建议我。

您有两个下拉列表，您希望根据用户在第一个下拉列表中选择的内容填充第二个下拉列表：

为此，请使用以下JavaScript：

如果您觉得这很有帮助，请将其标记为答案，谢谢

<select id="category_dropdown">
    <option value="Movies">Movies</option>
    <option value="Books">Books</option>
</select>

<select id='product_dropdown'></select>

var product_menu = [];

//Books
product_menu["Books"] = [
    "Author",
    "Title",
    "Publisher"
];

//Movies
product_menu["Movies"] = [
    "Actor",
    "Producer",
    "Movie Title"
];

//Setup listener on the category drop-down to update the products menu
var category_dropdown = document.getElementById("category_dropdown");
category_dropdown.addEventListener("change", function(){

  var product_dropdown = document.getElementById("product_dropdown");

    //Remove all options from product menu
    product_dropdown.innerHTML = "";

    //Now add new options
    var product_items = product_menu[category_dropdown.value];

    for(var i = 0; i < product_items.length; i++){
        var option = document.createElement('option');
        option.text = product_items[i];
        option.value = product_items[i];
        product_dropdown.add(option);
    }
});