前言
我们在进行web自动化时，经常遇到一些不好操作的元素，普通的元素定位和操作容易报错，如果我们使用的selenium的话，就可以使用selenium调用js脚本进行操作。在playwright 中也有类似的方法，使用page.evaluate()执行JavaScript脚本。
page.evaluate()和page.evaluate_handle()之间的唯一区别是page.evaluate_handle()返回JSHandle。
- page.evaluate() 返回调用执行的结果
- page.evaluate_handle()返回JSHandle
page.evaluate()
返回evaluate() 返回执行JavaScript脚本的结果，使用示例如下：
from playwright.sync_api import sync_playwrightdef run_js_script():with sync_playwright() as playwright:browser = playwright.chromium.launch(headless=False)context = browser.new_context()page = context.new_page()page.goto('https://www.baidu.com')print(page.evaluate("1 + 2"))# 关闭浏览器context.close()browser.close()run_js_script()
也可以执行一个函数，如下：
from playwright.sync_api import sync_playwrightdef run_js_script():with sync_playwright() as playwright:browser = playwright.chromium.launch(headless=False)context = browser.new_context()page = context.new_page()page.goto('https://www.baidu.com')print(page.evaluate("() => '拜仁慕尼黑'"))# 关闭浏览器context.close()browser.close()run_js_script()
注：如果传递给page.evaluate()的函数返回一个不可序列化的值，则page.evaluate()解析为undefined
示例
- 打印网页标题
执行document.title 获取页面的title，代码如下：
from playwright.sync_api import sync_playwrightdef run_js_script():with sync_playwright() as playwright:browser = playwright.chromium.launch(headless=False)context = browser.new_context()page = context.new_page()page.goto("https://www.baidu.com/")title = page.evaluate('document.title')print(title)page.pause()# 关闭浏览器context.close()browser.close()run_js_script()
- 操作元素示例
from playwright.sync_api import sync_playwrightdef run_js_script():with sync_playwright() as playwright:browser = playwright.chromium.launch(headless=False)context = browser.new_context()page = context.new_page()page.goto("https://www.baidu.com/")js = """document.getElementById('kw').value='playwright';document.getElementById('su').click();"""page.evaluate(js)page.pause()# 关闭浏览器context.close()browser.close()run_js_script()
页面如下：
page.evaluate_handle()
page.evaluate_handle()的返回值是JSHandle。
from playwright.sync_api import sync_playwrightdef run_js_script():with sync_playwright() as playwright:browser = playwright.chromium.launch(headless=False)context = browser.new_context()page = context.new_page()page.goto("https://www.baidu.com/")a_handle = page.evaluate_handle("document.body")result_handle = page.evaluate_handle("body => body.innerHTML", a_handle)print(result_handle.json_value())result_handle.dispose()page.pause()# 关闭浏览器context.close()browser.close()run_js_script()
总结
本文主要介绍了playwright执行js脚本的操作，与selenium一样，playwright同样可以执行js脚本来完成一些不便操作的元素。
