如何在木偶中执行javascript代码

我是木偶新手，正在尝试了解如何执行puppeteer中作为字符串值提供的javascript代码。

例如，值(从输入检索)可能如下所示：document.getElementById('selector').value='some_value';

我实现了以下代码

const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('https://www.southwest.com/', { waitUntil: 'domcontentloaded' });
const script = await page.evaluate("document.getElementById('LandingAirBookingSearchForm_originationAirportCode').value='Dallas'; document.getElementById('LandingAirBookingSearchForm_originationAirportCode').dispatchEvent(new Event('input',{bubbles:!0}));");
await browser.close();

但返回以下错误：

评估失败：TypeError：无法设置NULL的属性"value"

---

解决方案

1. 在回调中评估页面上的脚本
2. 等待ID为‘LandingAirBookingSearchForm_originationAirportCode’的元素后再执行脚本，以确保端已加载

const puppeteer = require('puppeteer');

(async function () {
    const browser = await puppeteer.launch(/*{headless: false}*/);
    const page = await browser.newPage();
    await page.goto('https://www.southwest.com/', { waitUntil: 'domcontentloaded' });
    await page.waitFor('#LandingAirBookingSearchForm_originationAirportCode');
    await page.evaluate(() => {
        document.getElementById('LandingAirBookingSearchForm_originationAirportCode').value='Dallas'; 
        document.getElementById('LandingAirBookingSearchForm_originationAirportCode').dispatchEvent(new Event('input',{bubbles:!0}));
    });
    await browser.close();
})();