在每 5 页获取后循环等待 2 秒

Question

我希望脚本调用在每 5 页后等待 2 秒。

我的要求是for 循环应该在pageData.Number 到达第5 页时等待2 秒。所以基本上，循环应该在每5 页后等待2 秒。

不知道如何检查页面是否到达第5页并等待2秒。

for (var i = 1; i <= pageData.Number; i++) {
  var pageRequest = $.getJSON(URL, function (data) {
    if (i % 5 == 0) {
      sleep(5000);
    }
    /* .... */
  }).fail(function () {
    errorPage.push(i);
  });
}

// from https://www.sitepoint.com/delay-sleep-pause-wait/
function sleep(milliseconds) {
  const date = Date.now();
  let currentDate = null;
  do {
    currentDate = Date.now();
  } while (currentDate - date < milliseconds);
}

Answer 1

您可以这样做 - 使用 async/await 和不使用 jQuery。

/**
 * @summary waits a specified number of seconds
 * @param {number} [seconds] seconds to wait
 * @returns {Promise<void>}
 * @link https://github.com/samliew/se-electionbot/blob/master/src/bot/utils.js#L910
 */
const wait = (seconds = 1) => new Promise((r) => setTimeout(r, seconds * 1e3));

/**
 * Your main function, async
 */
(async function () {
  
  const errorPage = [];
  const pageData = {
    Number: 10,
  };

  // Test URL
  const url = 'https://reqbin.com/echo/get/json';
  
  for (let i = 1; i <= pageData.Number; i++) {
  
    // Fetch url
    const data = await fetch(url).then(response =>
      // Convert data to json, or return null on error
      response.ok ? response.json() : errorPage.push(i) && null
    );
    
    // Data exists
    if(data) {
        // Do something with data
        console.log(`Request ${i} completed.`);
    }

    // Short wait after every fifth request
    if (i % 5 === 0) {
      console.log('Waiting for 2 seconds...');
      await wait(2);
    }
  }

  console.log('Done!');
})();

Answer 2

我认为你需要这样的东西。它使用 javascript remainder operator 和自定义睡眠功能。

for (var i = 1; i <= pageData.Number; i++) {
  //setTimeout(func, 2000);              
  var pageURL = Url + "?startDate=" + moment(startDate).format(dateFormat) + "&endDate=" + moment(endDate).add(1, 'day').format(dateFormat) + "&pageNumber=" + i;               
  var pageRequest = $.getJSON(URL, function (data) {
  if (i % 5 == 0) {
    sleep(2000);
  }
}

// from https://www.sitepoint.com/delay-sleep-pause-wait/
function sleep(milliseconds) {
  const date = Date.now();
  let currentDate = null;
  do {
    currentDate = Date.now();
  } while (currentDate - date < milliseconds);
}