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POHow to resolve this ReferenceError?
 

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  1. POHow to resolve this ReferenceError?
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    <p>I have a web application based on Django. I use the <a href="http://scrapy.org/" rel="nofollow">Scrapy Crawler</a> to crawl webpages. My goal, at the moment, is to be able to control the crawler from within a webpage using jQuery and AJAX requests.</p> <p>My theoretical setup is the following:</p> <ul> <li>On the webpage, I have a button. When I click the button, the crawler is started on the server-side.</li> <li>Once the crawler has started, I periodically send AJAX GET requests to the server using <a href="https://developer.mozilla.org/en-US/docs/DOM/window.setInterval" rel="nofollow"><code>window.setInterval</code></a> to find out how many webpages have been crawled so far.</li> <li>Once the crawler has finished, the GET requests should stop by using <a href="https://developer.mozilla.org/en-US/docs/DOM/window.clearInterval" rel="nofollow"><code>window.clearInterval</code></a>.</li> </ul> <p>These are the relevant lines from my current code:</p> <pre><code>$(document).ready(function() { // This variable will hold the ID returned by setInterval var monitorCrawlerId; $startCrawlerButton.on('click', function(event) { // This function should be run periodically using setInterval var monitorCrawler = function() { $.ajax({ type: 'GET', url: '/monitor_crawler/', // ... success: function(response) { // if the server sends the message that the crawler // has stopped, use clearInterval to stop executing this function if (response.crawler_status == 'finished') { clearInterval(monitorCrawlerId); } } }); }; // Here I send an AJAX POST request to the server to start the crawler $.ajax({ type: 'POST', url: '/start_crawler/', // ... success: function(response) { // If the form that the button belongs to validates correctly, // call setInterval with the function monitorCrawler defined above if (response.validation_status == 'success') { monitorCrawlerId = setInterval('monitorCrawler()', 10000); } } }); }); }); </code></pre> <p><strong>The problem:</strong> When I execute this code, I get this in Firefox's web console: </p> <pre><code>ReferenceError: monitorCrawler is not defined </code></pre> <p>The strange thing, however, is that the function <code>monitorCrawler</code> gets periodically executed anyway. But with every execution, I get the same error message again. If I put <code>monitorCrawler</code> outside of <code>$startCrawlerButton.on()</code> I still get the same errors. How can I resolve this? Since I'm a JavaScript newbie, any help is appreciated. Thank you very much! </p>
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    1. This table or related slice is empty.
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      1. POHow to resolve this ReferenceError?
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

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