node.js - 是否可以检测元素是否存在，然后提示用户输入？

Question

所以我有一个用例场景，我想检查是否存在某些东西，即安全复选框。如果是，则提示用户输入。我已经有另一个包含提示的包，但不确定如何实现将其与此结合起来。

var result = await new Promise( function (resolve, reject) {
    prompt.get(schema, function (err, result) {
        console.log('Command-line input received:');
        console.log('  password: ' + result.password);
        resolve(result);
        reject("error with prompt")
    })

});
console.log(result);
const browser = await puppeteer.launch({ headless: false });
const page = await browser.newPage();
await page.goto(url);

try {
    await page.waitFor("#security", { timeout: 3000 });
    // do something if there is a security box
}
catch (e) {
    console.error('no security');
}

编辑

只需使用 try catch 和 waitFor 即可进行检查

try {
    await page.waitFor("#login-form-os-captcha", { timeout: 1000 });
    console.log("there is captcha")
}
catch (e) {
    console.error('no captcha');
    // process.exit(1);
}

Answer 1

编辑 promise :

//...


// create a promise with the search in the page
searchElement(selector) => new Promise( function (resolve, reject){
  try{
     var elemAwait = await page.$eval(selector, el => el);
     resolve(selector,elemAwait);
  }catch{
     reject(selector,"Element doesn't exist");     
  }
});

// now, search element in the headless page
searchElement('#security')
.then(function(selector,el){
    // element is here
    prompt.get(schema, function (err, result) {

        console.log(selector+' is here with value:' + el.value);

    });
})
.catch(function(selector,msg){
     // element isn't here
    prompt.get(schema, function (err, result) {

        console.log(selector+" - "+msg);


    });
});

相对于:

https://developers.google.com/web/updates/2017/04/headless-chrome#cri

https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#pageselector

https://github.com/flatiron/prompt