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自定义选择器引擎

Custom selector engines

Playwright 支持自定义选择器引擎,已在 selectors.register() 注册。

Playwright supports custom selector engines, registered with selectors.register().

选择器引擎应具有以下属性:

Selector engine should have the following properties:

  • query 函数查询相对于 root 匹配 selector 的第一个元素。

    query function to query first element matching selector relative to the root.

  • queryAll 函数查询相对于 root 匹配 selector 的所有元素。

    queryAll function to query all elements matching selector relative to the root.

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,不能保证作为内容脚本运行。

By default the engine is run directly in the frame's JavaScript context and, for example, can call an application-defined function. To isolate the engine from any JavaScript in the frame, but leave access to the DOM, register the engine with {contentScript: true} option. Content script engine is safer because it is protected from any tampering with the global objects, for example altering Node.prototype methods. All built-in selector engines run as content scripts. Note that running as a content script is not guaranteed when the engine is used together with other custom engines.

创建页面之前必须注册选择器。

Selectors must be registered before creating the page.

注册根据标签名称查询元素的选择器引擎的示例:

An example of registering selector engine that queries elements based on a tag name:

baseTest.ts
import { test as base } from '@playwright/test';

export { expect } from '@playwright/test';

// Must be a function that evaluates to a selector engine instance.
const createTagNameEngine = () => ({
// 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));
}
});

export const test = base.extend<{}, { selectorRegistration: void }>({
// Register selectors once per worker.
selectorRegistration: [async ({ playwright }, use) => {
// Register the engine. Selectors will be prefixed with "tag=".
await playwright.selectors.register('tag', createTagNameEngine);
await use();
}, { scope: 'worker', auto: true }],
});
example.spec.ts
import { test, expect } from './baseTest';

test('selector engine test', async ({ page }) => {
// Now we can use 'tag=' selectors.
const button = page.locator('tag=button');
await button.click();

// We can combine it with built-in locators.
await page.locator('tag=div').getByText('Click me').click();

// We can use it in any methods supporting selectors.
await expect(page.locator('tag=button')).toHaveCount(3);
});