在文档上下文里执行脚本，并返回结果

/在文档上下文里执行脚本，并返回结果
(async () => {
  const browser = await puppeteer.launch({
      args: [\'--no-sandbox\'],
      timeout: 10000,
    });
  const page = await browser.newPage();
  await page.goto(\'http://www.163.com\');

  // Get the "viewport" of the page, as reported by the page.
  const dimensions = await page.evaluate(() => {
    return {
      width: document.documentElement.clientWidth,
      height: document.documentElement.clientHeight,
      deviceScaleFactor: window.devicePixelRatio
    };
  });

  console.log(\'Dimensions:\', dimensions);

  await browser.close();
})();

//直接传递字符串

Passing arguments to pageFunction:

const result = await page.evaluate(x => {
  return Promise.resolve(8 * x);
}, 7);
console.log(result); // prints "56"

A string can also be passed in instead of a function:

console.log(await page.evaluate(\'1 + 2\')); // prints "3"
const x = 10;
console.log(await page.evaluate(`1 + ${x}`)); // prints "11"

ElementHandle instances can be passed as arguments to the page.evaluate:

const bodyHandle = await page.$(\'body\');
const html = await page.evaluate(body => body.innerHTML, bodyHandle);
await bodyHandle.dispose();

Shortcut for page.mainFrame().evaluate(pageFunction, ...args).