Playwright - 如何检查元素是否在视口中？

Question

我有一个类似数组的节点对象（它是一个轮播），它们的顺序是在每次页面刷新时随机生成的，剧作家发现所有元素都是可见的，但其中一些元素在视口之外（基于收到的错误） ）。我需要确保在尝试单击该元素时该元素位于视口内，否则我会收到一条错误消息，指出该元素位于视口外。

如何确定类似数组对象的随机选取的节点元素是否确实在视口内？

Answer 1

Playwright 不幸的是 Puppeteer 中还没有像 isInterSectingViewport 这样的方法。(likethis)

所以 Playwright 的作者在 Slack 社区帮助我（你可以在官方网站上找到它）。

    const result = await page.$eval(selector, async element => {
      const visibleRatio: number = await new Promise(resolve => {
        const observer = new IntersectionObserver(entries => {
          resolve(entries[0].intersectionRatio);
          observer.disconnect();
        });
        observer.observe(element);
        // Firefox doesn't call IntersectionObserver callback unless
        // there are rafs.
        requestAnimationFrame(() => {});
      });
      return visibleRatio > 0;
    });

我使用这个方法的案例： 我想知道在单击某个元素后 - 我已经滚动到另一个元素。不幸的是，boundingBox 方法对我的情况没有帮助。

您也可以将此功能添加到我的 BasePage 类中

/**
     * @returns {!Promise<boolean>}
     */
  isIntersectingViewport(selector: string): Promise<boolean> {
    return this.page.$eval(selector, async element => {
      const visibleRatio: number = await new Promise(resolve => {
        const observer = new IntersectionObserver(entries => {
          resolve(entries[0].intersectionRatio);
          observer.disconnect();
        });
        observer.observe(element);
        // Firefox doesn't call IntersectionObserver callback unless
        // there are rafs.
        requestAnimationFrame(() => {});
      });
      return visibleRatio > 0;
    });
  }

附注 事实上，除了一行代码外，所有代码均取自GitHub Puppeteer

中 isInterSectingViewport 方法的实现

Answer 2

使用 css 选择器检查元素是否在视口中：

import { test, expect, devices } from '@playwright/test'

const url = 'https://example.com'
const selector = 'h1'

test.use({
    headless: false,
    browserName: 'webkit',
    ...devices['iPhone 13 Mini'],
})

test('visibility', async ({ page }) => {
    await page.goto(url)
    const box = await page.locator(selector).boundingBox() // it contains x, y, width, and height only
    let isVisible = await page.evaluate((selector) => {
        let isVisible = false
        let element = document.querySelector(selector)
        if (element) {
            let rect = element.getBoundingClientRect()
            if (rect.top >= 0 && rect.left >= 0) {
                const vw = Math.max(document.documentElement.clientWidth || 0, window.innerWidth || 0)
                const vh = Math.max(document.documentElement.clientHeight || 0, window.innerHeight || 0)
                if (rect.right <= vw && rect.bottom <= vh) {
                    isVisible = true
                }
            }
        }
        return isVisible
    }, selector)
    await expect(isVisible).toBeTruthy()
})

Answer 3

const firstId = "#someId"; 

// it happens that I am evaluating in a frame, rather than page 
const result = await frame.evaluate((firstId) => {

  // define a function that handles the issue
  // returns true if element is within viewport, false otherwise 
  function isInViewport(el) {

    // find element on page 
    const element = document.querySelector(el); 

    const rect = element.getBoundingClientRect();
    return (
      rect.top >= 0 &&
      rect.left >= 0 &&
      rect.bottom <=
        (window.innerHeight || document.documentElement.clientHeight) &&
      rect.right <=
        (window.innerWidth || document.documentElement.clientWidth)
    );
  }; 

  return isInViewport(firstId); 

}, firstId);



// back to node context 
console.log(result); 

Answer 4

除了cardinalX answer。 您可以使用 page.waitForFunction 创建辅助函数来等待元素出现在视口中

import { Page } from '@playwright/test';

export const waitToBeInViewport = async (
  page: Page,
  selector: string,
) => page.waitForFunction(async (selectorParam: string) => {
  const element = document.querySelector(selectorParam);
  const visibleRatio: number = await new Promise((resolve) => {
    const observer = new IntersectionObserver((entries) => {
      resolve(entries[0].intersectionRatio);
      observer.disconnect();
    });
    observer.observe(element);
    requestAnimationFrame(() => { });
  });
  return visibleRatio > 0; // where 0 - element has just appeared, and 1 - element fully visible;
}, selector);

Answer 5

Playwright 添加了一个 feature 来启用使用“expect”进行检查。使用信息如下：

 (method) LocatorAssertions.toBeInViewport(options?: {
    ratio?: number;
    timeout?: number;
}): Promise<void>
Ensures the Locator points to an element that intersects viewport, according to the intersection observer API.

Usage

const locator = page.getByRole('button');
// Make sure at least some part of element intersects viewport.
await expect(locator).toBeInViewport();
// Make sure element is fully outside of viewport.
await expect(locator).not.toBeInViewport();
// Make sure that at least half of the element intersects viewport.
await expect(locator).toBeInViewport({ ratio: 0.5 });