可扩展性

Custom selector engines

Custom selector engines

Playwright 支持自定义选择器引擎，使用 selectors.register(name, **kwargs) 注册。

选择器引擎应具有以下属性：

create 函数，用于创建从 root（根是 Document、ShadowRoot 或 Element）到 target 元素的相对选择器。
query 函数，用于查询相对于 root 匹配 selector 的第一个元素。
queryAll 函数，用于查询相对于 root 匹配 selector 的所有元素。

默认情况下，引擎直接在框架的 JavaScript 上下文中运行，例如，可以调用应用程序定义的函数。要将引擎与框架中的任何 JavaScript 隔离，但保留对 DOM 的访问权限，请使用 {contentScript: true} 选项注册引擎。内容脚本引擎更安全，因为它可以防止对全局对象的任何篡改，例如更改 Node.prototype 方法。所有内置选择器引擎都作为内容脚本运行。请注意，当引擎与其他自定义引擎一起使用时，不保证作为内容脚本运行。

注册基于标签名称查询元素的选择器引擎的示例：

Sync
Async

tag_selector = """
    // Must evaluate to a selector engine instance.
    {
      // Returns the first element matching given selector in the root's subtree.
      query(root, selector) {
        return root.querySelector(selector);
      },

      // Returns all elements matching given selector in the root's subtree.
      queryAll(root, selector) {
        return Array.from(root.querySelectorAll(selector));
      }
    }"""

# register the engine. selectors will be prefixed with "tag=".
playwright.selectors.register("tag", tag_selector)

# now we can use "tag=" selectors.
button = page.locator("tag=button")
button.click()

# we can combine it with other selector engines using `>>` combinator.
page.locator("tag=div >> span >> \"click me\"").click()

# we can use it in any methods supporting selectors.
button_count = page.locator("tag=button").count()

tag_selector = """
    // Must evaluate to a selector engine instance.
    {
      // Returns the first element matching given selector in the root's subtree.
      query(root, selector) {
        return root.querySelector(selector);
      },

      // Returns all elements matching given selector in the root's subtree.
      queryAll(root, selector) {
        return Array.from(root.querySelectorAll(selector));
      }
    }"""

# register the engine. selectors will be prefixed with "tag=".
await playwright.selectors.register("tag", tag_selector)

# now we can use "tag=" selectors.
button = page.locator("tag=button")
await button.click()

# we can combine it with other selector engines using `>>` combinator.
await page.locator("tag=div >> span >> \"click me\"").click()

# we can use it in any methods supporting selectors.
button_count = await page.locator("tag=button").count()

Custom selector engines​

Custom selector engines