網頁抓取資料-有解無憂

我得到一個

參考錯誤：終端 A 未定義

在第 48 行。我不確定我做錯了什么。

writeStream.write(`Terminal A,Terminal B,Terminal C/D \n`);


var minutes = 1, timerInerval = minutes * 60 * 1000;


function TerminalOccupancyData() {

 
  request('https://www.laguardiaairport.com/to-from-airport/parking', (error, response, html) => {
    // Check there is no error
    if (!error && response.statusCode == 200) {
      // using cheerio library to load the website page html
      const $ = cheerio.load(html);

      $('.terminal-left').each((span, el) => {
        // Find the element using the class
        const terminalA = $(el)
          .find('.terminal-percentage')
          .text()
          .replace(/% Full/, '');

        const terminalB = $(el)
          .find('.terminal-percentage')
          .text()
          .replace(/% Full/, '');

        const terminalCD = $(el)
          .find('.terminal-percentage')
          .text()
          .replace(/% Full/, '');
      });

      console.log('\nTerminal Data scraped ... \n');
    }

  });

  // Export to file to upload to database
  writeStream.write(`${terminalA},${terminalB},${terminalCD} \n`);
}

setInterval(TerminalOccupancyData, timerInerval);

uj5u.com熱心網友回復：

您在這里遇到的問題是您writeStream.write(...)與它參考的變數不在同一范圍內。由于您沒有嘗試從外部函式回傳任何值，我相信可以解決您的問題的方法只是將該陳述句移動到.each()回呼函式中，如下所示：

function TerminalOccupancyData() {

 
  request('https://www.laguardiaairport.com/to-from-airport/parking', (error, response, html) => {
    // Check there is no error
    if (!error && response.statusCode == 200) {
      // using cheerio library to load the website page html
      const $ = cheerio.load(html);

      $('.terminal-left').each((span, el) => {
        // Find the element using the class
        const terminalA = $(el)
          .find('.terminal-percentage')
          .text()
          .replace(/% Full/, '');

        const terminalB = $(el)
          .find('.terminal-percentage')
          .text()
          .replace(/% Full/, '');

        const terminalCD = $(el)
          .find('.terminal-percentage')
          .text()
          .replace(/% Full/, '');

          // Export to file to upload to database
          writeStream.write(`${terminalA},${terminalB},${terminalCD} \n`);
      });

      console.log('\nTerminal Data scraped ... \n');

    }

  });

  
}

setInterval(TerminalOccupancyData, timerInerval);

轉載請註明出處，本文鏈接：https://www.uj5u.com/qianduan/359250.html

標籤：节点.js 文件网页抓取导出到 csv

上一篇：如何在aspnetcorewebAPI上正確地將串列轉換為IQueryable

下一篇：將3列轉換為2列-Python