使用 selenium Nodejs 等待异步函数

Question

我正在创建一个小程序，当您使用 selenium 在 google 上搜索内容时返回所有链接标题的名称

代码如下：

const {Builder,By, Key, until} = require('selenium-webdriver');

driver = new Builder().forBrowser("firefox").build();

var search_query='tigers';

(async()=>{

await driver.get(`https://www.google.com/search?q=${search_query}`);

await driver.findElements(By.css('h3')).then((search_results)=>{ 
 for (var i = 0; i < search_results.length; i++)
  search_results[i].getText().then((text)=>{console.log(text);})
});

console.log('...Task Complete!')
})();

当你运行它时，输出如下：-

...Task Complete!
Tiger - Wikipedia
Top stories
Tigers (2014 film) - Wikipedia
Detroit Tigers (@tigers) · Twitter
Tiger | Species | WWF
Videos
Official Detroit Tigers Website | MLB.com
Tiger | WWF
Tiger - National Geographic Kids
Tiger guide: species facts, how they hunt and where to see in ...
Related searches
Images
Description

显然应该在整个功能完成后记录...Task Complete!

我不明白我做错了什么我使用了适当的await 关键字来保持代码流有序，是then() 中的错误吗？

Answer 1

由于您的 .then(()=>...) 没有返回 Promise，所以开头的 await 关键字什么也不做。 Node 已经开始承诺获取 h3，获取它们的文本内容并记录它们，但是您放错位置的 await 并没有告诉 Node 等待所有这些完成。你会想await获取元素，然后同步循环遍历所有元素，awaiting文本，然后同步打印文本，最后同步打印"...Task Complete!"

const { Builder, By, Key, until } = require('selenium-webdriver');

const driver = new Builder().forBrowser("firefox").build();

const search_query = 'tigers';

(async () => {
    await driver.get(`https://www.google.com/search?q=${search_query}`);

    const h3Elements = await driver.findElements(By.css('h3'));
    for (const h3 of h3Elements) {
        const text = await h3.getText();
        console.log(text);
    }

    console.log('...Task Complete!')
})();

如果你想减少额外的变量，你可以这样做：

const { Builder, By, Key, until } = require('selenium-webdriver');

const driver = new Builder().forBrowser("firefox").build();

const search_query = 'tigers';

(async () => {
    await driver.get(`https://www.google.com/search?q=${search_query}`);

    const h3Elements = await driver.findElements(By.css('h3'));
    for (const h3 of h3Elements) {
        console.log(await h3.getText());
    }

    console.log('...Task Complete!')
})();