javascript - 如何将从评估返回的变量传递给Nightmare.js中的另一个评估

Question

我目前正在尝试使用Nightmare.js和vo来提取表的数据。我要提取的表具有多个页面，我必须将该表的全部提取到一个外部HTML字符串中，该字符串稍后将转换为JSON。我正在使用的代码正在循环运行，每个循环都包含一个validate()函数。我想做的是有一个变量，该变量保留要提取的数据(字符串)，并在每个循环中向其中添加新数据。但是，当我无法将变量从先前的validate()发送到下一个时，我遇到了一个问题。这是我的代码的运行功能。

function *run() {
  var totalPageNumber = "";
  var nightmare = Nightmare({ show: true });
  yield nightmare
    .goto('https://www.svgame168.com/IGKiosk/guest/login.aspx')
    .select('#ctl00_ddlLanguage', 'th-TH')
    .wait(3000)
    .insert('input[name="ctl00$ContentPlaceHolder1$Login1$UserName"]', userName)
    .insert('input[name="ctl00$ContentPlaceHolder1$Login1$Password"]', password)
    .click('#ctl00_ContentPlaceHolder1_Login1_LoginButton')
    .wait(3000)
    .goto('https://www.svgame168.com/IGKiosk/playermgt/Default.aspx')
    .click('#ctl00_ContentPlaceHolder1_searchBtn')
    .wait(6000)
    .evaluate(function () {
      var result = "";
      var nextPageExist = document.evaluate("//a[contains(., '>')]", document, null, XPathResult.ANY_TYPE, null );
      nextPageExist = nextPageExist.iterateNext();result = document.querySelector("#ctl00_ContentPlaceHolder1_dataGridView").outerHTML;
      var totalPageNumber = document.querySelector("#main_content_table > tbody > tr > td > table:nth-child(5) > tbody > tr > td > table > tbody > tr > td > div:nth-child(4) > span > div:nth-child(1)");

      if (nextPageExist != null){
        nextPageExist.className += " nextPageExist1";
      }
      return totalPageNumber;
    })

  for (var i = 2; i <= 11; i++) {
    console.log("Currently on page " + i);
    yield nightmare
      .click(".nextPageExist" + (i - 1))
      .wait(6000)
      .evaluate(function (result) {
        var nextPageExist = document.evaluate("//a[text()='>']", document, null, XPathResult.ANY_TYPE, null );
        nextPageExist = nextPageExist.iterateNext();

        console.log(result);
        result += document.querySelector("#ctl00_ContentPlaceHolder1_dataGridView").outerHTML;
        //console.log(result);
        if (nextPageExist != null){
          var pageNumber = document.querySelector("#main_content_table > tbody > tr > td > table:nth-child(5) > tbody > tr > td > table > tbody > tr > td > div:nth-child(4) > span > div:nth-child(2) > span").innerHTML
          pageNumber = pageNumber.replace(/\D/g,'');
          nextPageExist.className += " nextPageExist" + pageNumber;
        }
        return result
      })
  }
  yield nightmare
    .end()
    .then(function (result) {
      console.log(tabletojson.convert(result));
    })
    .catch(function (error) {
      console.error('Search failed:', error);
    });
}

我怀疑我在第二个评估中收到变量时的语法错误，但是找不到解决方案。我尝试使用它，它仍然会给出错误。

      .evaluate(function (result) {
        var nextPageExist = document.evaluate("//a[text()='>']", document, null, XPathResult.ANY_TYPE, null );
        nextPageExist = nextPageExist.iterateNext();

        console.log(result);
        result += document.querySelector("#ctl00_ContentPlaceHolder1_dataGridView").outerHTML;
        //console.log(result);
        if (nextPageExist != null){
          var pageNumber = document.querySelector("#main_content_table > tbody > tr > td > table:nth-child(5) > tbody > tr > td > table > tbody > tr > td > div:nth-child(4) > span > div:nth-child(2) > span").innerHTML
          pageNumber = pageNumber.replace(/\D/g,'');
          nextPageExist.className += " nextPageExist" + pageNumber;
        }
        return result
      }, result)

如果我从评估的每一行中删除“结果”变量，则以上代码将起作用。

Answer 1

以下是从评估方法返回结果并将其存储并移至下一页的方法

return nightmare
        .click(".nextPageExist" + (i - 1))
        .wait(5000) // wait till the page is loaded
        .evaluate(() => {
           //extract data from table
           //return the data
           return result
         })
        .then((result) => {
           //recieve the data from previous step 
           
           //add the result to an global array
           tableResults.push(result);

         })
     

上面的代码可以像下面这样在数组化简器中进行迭代，与使用for循环相比，更推荐使用化简器。

let pages = [1, 2, 3, 4] // assuming there are 4 pages, create an array with a 
                         //length of 4

pages.reduce(accumulator, currentValue, index, arr)
{
      accumulator.then(() => {
         return nightmare
        .click(".nextPageExist" + (currentValue - 1))
        .wait(5000) // wait till the page is loaded
        .evaluate(() => {
           //extract data from table
           //return the data
           return result
         })
        .then((result) => {
           //recieve the data from previous step 
           
           //add the result to an global array
           tableResults.push(result);

         })
      })
    

}, Promise.resolve());