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 evaluate() 返回执行 JavaScript 脚本的结果，使用示例如下：
from playwright.sync_api import sync_playwright
def 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()
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也可以执行一个函数，如下：
from playwright.sync_api import sync_playwright
def 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()
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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_playwright
def 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()
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操作元素示例
from playwright.sync_api import sync_playwright
def 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()
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页面如下：
page.evaluate_handle()
page.evaluate_handle()的返回值是 JSHandle。
from playwright.sync_api import sync_playwright
def 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()
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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。
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