![]() The solution is to use JQuery.when() method. The downside of this approach is that a new AJAX call cannot start until the previous one ends, wasting valuable time. A simple approach could be to just stack all three AJAX calls to start as soon as the previous one finishes. Consider an example website that performs a separate AJAX call to get the post content, one to get the post image, and another one for post reviews. ![]() One such situation is a website that loads parts of its content as static html, and other parts dynamically through various APIs. Performing several simultaneous AJAX calls is a very efficient way to handle certain scraping situations. Multiple simultaneous AJAX calls using $.when() default retry timer is 60000ms, AJAX timeout should be a few seconds lower. In the example below, if any response is not received from the server within 55000ms, AJAX call will timeout and code will proceed to run as normal. To avoid such a scenario a local AJAX timeout should be set up to be just below the step retry timeout (default is 60000 ms). Depending on the specific code, this can cause instability to the robot and unnecessary error logging. This means that even though the step has already finished, the code inside the GET done block will run and trigger a done(). ![]() However, depending on how the server is configured, it might return a valid response after a significant delay, sometimes above our locally set step retry timeout. status code 404) or fails to respond whatsoever. It works fine when the server returns a failed response (E.g. fail() block and force a step retry after our preset retry timeout. fail() block and move along with our scraping, or omit the. If the GET fails, we can either call a done() function inside the. A GET request is performed, and since it is asynchronous, step done() function is placed inside the GET done block. One issue with AJAX requests inside a step function is that the step global retry timeout and the AJAX timeout are independent, and in certain scenarios this can cause problems.Ĭonsider this example. Example incorrect and correct done() placement in AJAX: INCORRECTĮxample incorrect and correct AJAX looping: INCORRECT Also, multiple AJAX calls shouldn’t be made inside a loop, instead a new step for the AJAX should be created and queued up with next() inside the loop. Since AJAX is asynchronous, step done() should always be placed inside the AJAX callback function. Basic AJAX usage within Web Robots scraperīest and simplest way to perform AJAX calls with the scraper is to use JQuery $.ajax() or the simplified $.get(), $.post() and $.getJSON() methods.
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